Search as the user types

Fixes #323.

This does away with the separate `SearchResult` and instead applies the search to the currently viewed tab on the main screen (Available, Installed, Updates). When filtering the Available list, it filters the currently selected category.

Note however that there are still times when the old style `SearchDialog` will be shown over the top of the action bar rather than the `SearchView` within the action bar. These times include:
 * When a user with a hardware keyboard starts typing from the main screen.
 * On older devices with a "search" hardware button.
 * Probably some other cases (I think when there is not enough screen real estate, but haven't seen that happen).

In cases where this dialog is shown, filtering the lists as you type does not seem to be an option. I tried to figure out how to do that, but failed. If someone else figures it out, that would be great. However, when the search is submitted, it will hide the `SearchDialog` and populate the `SearchView`, focus it, and apply the search appropriately.

There is a script in the `F-Droid/tools/` subdirectory which will consecutively send various intents to F-Droid relating to search. This includes Play, market, Amazon search links. For good measure, I also made it send intents to do with viewing app details. This should probably be made into a proper instrumented test at some point, but I didn't have the time to figure out how to do that. Maybe a project for future @pserwylo.

One unknown is the performance implications. There is no problems on my Nexus 4 with Android 5.0. My Chinese/ebay/$30/Android 2.3.4 device seems good enough too.

See merge request !177

The system's are sometimes wrong, e.g. unexpected names. This also helps
our support across different Android versions without having to worry as
much about the system's language support.

Fixes #503.

Translators:

Dario Tordoni      Italian
Elia Argentieri    Italian
Enol Puente        Asturian
halcyonest         Korean
M2ck               French
relan              Russian
Tobias Bannert     German
Дмитрий Михирев    Russian

In addition, added a @Nullable constraint on the categorySpinner
and a null guard when resuming the fragment to handle possible
null cases (though I don't think there will be any).

This caused the entire list view to e animated when navigating
back to the Available tab. Tried switching the `animateLayoutChanged=true`
to a child view only containing the category spinner, but this is not how
the animation handling works. It needs to animate both the thing being
hidden/shown, and also the next sibling of that thing to work properly.
Thus, moving the spinner to its own child and leaving the list didn't work.

As per CR comment. These don't really ressemble URIs very much, so I
don't think they will require sanitization like this at all.

Removed the option to search the currently selected category, as suggested
by others on gitlab.

% means wildcard, not case insensitive in sqlite3.

When calling `finish()` after handling an intent to show app details,
the ability to navigate "up" disappears.

Translators:

Adrià García-Alzórriz      Catalan
agilob                     Polish
Ajeje Brazorf              Sardinian
bd339                      Danish
Benedikt Geißler           German
Danial Behzadi             Persian
Daniil Stryukov            Ukrainian
halcyonest                 Korean
ikmaak                     Dutch
Ldm Public                 French
Massimiliano Caniparoli    Italian
Mladen Pejaković           Serbian
Olexandr Nesterenko        Ukrainian
Phạm Nguyễn Hoàng          Vietnamese
relan                      Russian
Tobias Bannert             German

Speed up "Saving Application Details" part of repo update

Fixes 506.

This does the thing mentioned in 506 (renaming temp table, rather than copying data). In the process, I also identified that the temp tables were missing key indexes which slowed the process down. This fix took the update time from ~100 seconds to ~60 seconds on my Nexus 4.

Below are a couple of log cats from before and after the change (this logging is not part of this MR, it was just for diagnosing the problem).

*Before change:*

```
            AppProvider  D  Calculating whether apps are compatible, based on whether any of their apks are compatible
                         D  Update compatible flags took 20244ms
                         D  Calculating suggested versions for all apps which specify an upstream version code.
                         D  Update suggested from upstream took 17808ms
                         D  Calculating suggested versions for all apps which don't specify an upstream version code.
                         D  Update suggested from latest took 129ms
            AppProvider  D  Update icon URLs took 7879ms
          UpdateService  I  Updating repo(s) complete, took 104 seconds to complete.
```

*After change:*

```
            AppProvider  D  Calculating whether apps are compatible, based on whether any of their apks are compatible
                         D  Update compatible flags took 1047ms
                         D  Calculating suggested versions for all apps which specify an upstream version code.
                         D  Update suggested from upstream took 601ms
                         D  Calculating suggested versions for all apps which don't specify an upstream version code.
                         D  Update suggested from latest took 136ms
                         D  Update icon URLs took 887ms
          UpdateService  I  Updating repo(s) complete, took 63 seconds to complete.
```



See merge request !179

The idnexes which are added are for those columns which
are used to calculate information such as latest upstream version.
These queries use subqueries which seemed to be adversely
impacted by the lack of indexes.

In total, reduced update time on test device from just over 100 seconds
to just over 60 seconds.

Looks like a non-trivial amount of work is done in the constructor
interrogating the features of the current device. This only needs
to be done once.

This requires renaming the old app/apk tables to be deleted and
the temp ones to be renamed. This is done in a transaction to
ensure we always have at least `fdroid_app` and `fdroid_apk`.
Well, two transactions, one for renaming the `fdroid_app` table
and one for `fdroid_apk`.

These objects/strings were probably useful at some point. They no longer
are.

I was too fast to remove unused code and missed the continue.

Translators:

agilob                Polish
Ajeje Brazorf         Sardinian
Alberto Moshpirit     Spanish
Daniil Stryukov       Ukrainian
Enol Puente           Asturian
Jaroslav Lichtblau    Czech
Ldm Public            French
lucnsy                Chinese (China)
Marcelo Santana       Portuguese (Brazil)
Mladen Pejaković      Serbian
naofum                Japanese
relan                 Russian

Fix 324 : Out of memory errors while updating repos.

Fixes #324, but in the process makes the updater take a lot longer. My benchmarks tell me that an update which used to take approx 30 seconds on my Nexus 4 now takes about 50-55 seconds. This is because it first inserts the apps into the database (in a temp table) and then subsequently copies that table to the actual table. This means there is a lot more disk access than before.

I'm open for discussion on whether this tradeoff is worth it - however I'll caution that there is always going to be a tradeoff between faster and more memory vs slower and less memory. This is the case with all software, and perhaps more so with memory constrained devices such as phones. Also, as the repo index grows (until perhaps we are able to extract the app descriptions in the future), this will become more of an issue.

I'd also like this to be CR'ed properly before merging, because it changes some important code around the repo updater. It is important because security, and it is also important because it is the main thing that F-Droid needs to do (get a list of apps to show the user).

See merge request !173

Translators:

ageru                French
Ajeje Brazorf        Sardinian
Alberto Moshpirit    Spanish
enolp                Asturian
Ldm Public           French
lucnsy               Chinese (China)
Mladen Pejaković     Serbian
naofum               Japanese