Translators:

Adrià García-Alzórriz    Catalan
Adrià García-Alzórriz    Spanish
Marcelo Santana          Portuguese (Brazil)
Mladen Pejaković         Serbian
naofum                   Japanese
Tobias Bannert           German
Verdulo                  Esperanto
Verdulo                  Polish
YFdyh000                 Simplified Chinese

CleanCacheService

This creates `CleanCacheService` to do all of the cache clean up at the lowest possible priority.  It also adds a preference to set how long to keep cached APKs.

See merge request !260

Updater speed improvements during "Saving Application Details"

I've been able to reproduce #324 OutOfMemory errors on an emulator with 12MiB of heap space. This branch did _not_ have an OOM error when updating with F-Droid and F-Droid Archive repos enabled. They successfully update without problem.

Fixes #45.

The "Saving Application Details" stage of repository updating is where each apk has its suggested version calculated, icon URLs calculated, etc. These all require [correlated subqueries](https://en.wikipedia.org/wiki/Correlated_subquery) resulting in a full scan of the apk table for each row in the app table. This takes in the order of 25 seconds on my Moto X 2nd Gen.

This branch improves this process by doing the queries in an [sqlite in-memory database](https://sqlite.org/inmemorydb.html), with the results transferred to the database on disk when done. The time required drops from 25 seconds to ~0.5 seconds on my device.

*Note:* I was hoping this would also improve the "Processing ..." Part of the udpater, given it was inserting into an in memory table instead of on disk. If it did have any effect, it was negligible though, so that part is still likely slower than it could be. Each 50 apps (and their associated apks) takes between 150ms and 500ms on my Moto X.

*Secondary Note:* When creating the in memory database, I create indexes for some columns as per before. This technically should slow down the inserts we do, however in practice they had almost no effect. As such, I've left the index creation there because it is required for the correlated subqueries to not suck. 

See merge request !269

Security-sensitive code should not be changed unless there is a good reason
to do so.  It is too easy to introduce bugs.  This change does not address
an issue, so I'm reverting it. See comment in javadoc header for the class.

This reverts commit 20747183 for just the
RepoUpdater.java file.

This schedules CleanCacheService to run regularly, and delete files older
than the value set in the new "Keep cached apps" preference. It auto-
migrates the old "Cache packages" pref to the new one.  The default cache
time for people who did not have "Cache packages" enabled is one day.

This moves the cache file deletion to a dedicated IntentService that runs
at the lowest possible priority.  The cache cleanup does not need to happen
with any kind of priority, so it shouldn't delay the app start or take any
resources away from foreground processes.

This also changes the logic around the "Cache packages" preference. The
downloader always saves APKs, then if "Cache packages" is disabled, those
APKs are deleted when they are older than an hour.

This also simplifies Utils.deleteFiles() since the endswith arg is no
longer needed.

* if there is a file there, remove it

The paths are all from the system, so are safe. No SanitizedFile is needed.
Plus, this method was not checking if the original and sanitized versions
where different, and instead just creating the sanitized version. I worry
that could cause odd bugs.

By putting these comments into javadoc, they are directly describing the
code where it is, and there are many tools in IDEs for searching, viewing,
sorting, etc. javadoc comments.  Plain comments do not have those tools.

Just trying to keep the code as close to what is actually used as possible.

Translators:

Ajeje Brazorf     Sardinian
Allan Nordhøy     Norwegian Bokmål
Paresh Chouhan    Hindi
Sérgio Marques    Portuguese (Portugal)
tacsipacsi        Hungarian

Fixes for priv extension install

For now, disable install of privileged extension on Android >=5.1 until we found better methods.
Also, fix crash of dialogs on Android 6 using a workaround for transparent activities and some code simplifications.

See merge request !259

CI: Bump image, use 64-bit emulator

Since the base image is now 200MB smaller, this one too. Also updates
the SDK to 25.1.3.

See merge request !271

Enable some more PMD rules



See merge request !270

This way, error lines like this one:

    Waiting for emulator to start: unknown: error: no devices found

Become:

    Waiting for emulator to start: error: no devices found

Otherwise, we'd interpret this as "booting", which is wrong:

     $ adb -e shell getprop init.svc.bootanim
    * daemon not running. starting it now on port 5037 *
    * daemon started successfully *
    error: no devices found

Since the base image is now 200MB smaller, this one too. Also updates
the SDK to 25.1.3.

This works on statements, not expressions, so it's a lot easier and
saner to obey than UselessParentheses.

We already obey them.

This increases the speed of the complex queries required at the end
of the update process to:
 * calculate suggested version codes
 * figure out icon urls
 * etc,
by two orders of magnitude.

This was there as a workaround for #1, but that has subsequently
been fixed. Thus, the hack is no longer required. Also removed an
additional `AND` because it is already performed in the `JOIN`.
I supsect this last one would've been eliminated by the sqlite
optimizer anyway, but the query is slightly simpler now.

This fix doesn't improve performance as much as I'd hoped, but it
is something.

Its first translations were added in the previous commit, pulled from
Weblate.

Translators:

Danial Behzadi            Persian
fastest noob              Turkish
Fert Bálint               Hungarian
Green Lunar               Hebrew
Jean-Baptiste             French
Karola Marky              Japanese
Kristjan Räts             Estonian
Licaon Kter               Romanian
Marian Hanzel             Slovak
Mohamad Hasan Al Banna    Indonesian
naofum                    Japanese
Tobias Bannert            German
YFdyh000                  Simplified Chinese

Added cancel action to notifications.

![Screenshot__Apr_27__2016_2-41-30_AM_](/uploads/7756406732c8583117532e5fed151a2c/Screenshot__Apr_27__2016_2-41-30_AM_.png)

See merge request !267

Don't show "Updates Available" if auto updates is enabled.

This notification is redundant in this circumstance.

See merge request !268

This notification is redundant in this circumstance.

A few Java fixes and tweaks, enable more PMD rules



See merge request !266

Also, Log.d in tests don't make much sense - replace by Log.i. This way
it's easier to limit all Log.d calls to Utils.java.

This happened to me when I clicked on an app link for a new app which
was already in the repo, but I had not ran an index update yet since the
app got built. Stack trace prior to the fix follows.

	java.lang.RuntimeException: Unable to destroy activity {org.fdroid.fdroid/org.fdroid.fdroid.AppDetails}: java.lang.NullPointerException:
	Attempt to invoke virtual method 'void android.support.v4.content.LocalBroadcastManager.unregisterReceiver(android.content.BroadcastReceiver)' on a null
	object reference
		at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3865)
		at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3883)
		at android.app.ActivityThread.-wrap5(ActivityThread.java)
		at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1417)
		at android.os.Handler.dispatchMessage(Handler.java:102)
		at android.os.Looper.loop(Looper.java:148)
		at android.app.ActivityThread.main(ActivityThread.java:5461)
		at java.lang.reflect.Method.invoke(Native Method)
		at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
		at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
	Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void
	android.support.v4.content.LocalBroadcastManager.unregisterReceiver(android.content.BroadcastReceiver)' on a null object reference
		at org.fdroid.fdroid.AppDetails.unregisterDownloaderReceivers(AppDetails.java:469)
		at org.fdroid.fdroid.AppDetails.onDestroy(AppDetails.java:569)
		at android.app.Activity.performDestroy(Activity.java:6422)
		at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1143)
		at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3852)
		... 9 more

See #632.

Found by Android Studio.