front: Consolidate native lib loading to CoreInterfaceNative.

Consolidate loading the ae-bridge/sdl/core/front-end libraries to one
place.  Simplifies maintenance.  Putting it in CoreInterfaceNative is
also a better place because it guarantees that those 4 libraries will
always be loaded before any other calls to the native methods.

Also, moving the lib loading functions to CoreInterfaceNative from
FileUtil ensures that those 4 libraries will always be loaded before
any of the plugins.
front: Update library sanity check to include SDL2.
ae-bridge: Pass config by console args rather than JNI.
cleanup: Format whitespace, no functional changes.
front: Reduce logcat chatter.
ae-bridge: Reduce logcat chatter.
front-end: Reduce diff with upstream.

I don't think we need this logging any longer...
front: Try to guarantee no slow EGL config, add more EGL logging.
bugfix: Fix AudioTrack IllegalStateException.

Not quite sure how to replicate this bug but I see a lot of it in the
crash reports:

 java.lang.IllegalStateException: play() called on uninitialized AudioTrack.
 at android.media.AudioTrack.play(AudioTrack.java:883)
 at paulscode.android.mupen64plusae.CoreInterfaceNative$1.run(CoreInterfaceNative.java:356)

I think the bug is related to an existing audio track not quitting
before initializing a new one.  If I am correct, then the bug was
introduced in commit 6cfff95c269a3aad48a138d1cd5fcb81e383b4b9, where
some SDL2 example code was cut & pasted into the app overtop one of our
previous bugfixes.

To (hopefully) fix the bug, I just reverted the code to what it was
prior to commit 6cfff95c269a3aad48a138d1cd5fcb81e383b4b9 (with a few
minor changes).
front: Properly cleanup AudioTrack resources.

The SDL2 example that this implementation drew from has a bug.
AudioTrack.release() needs to be called when shutting down the audio
thread.  The O/S creates a second native thread behind the scenes for
AudioTrack (in addition to our Audio thread we create in Java). Without
this bugfix, two things occur:
 - Somehow an additional AudioTrack thread gets created and orphaned
   during core startup.
 - The AudioTrack thread never gets killed during core shutdown.

I'm not sure if the first effect creates any hit to performance or not.
The second side-effect is currently obscured by the ASDP bug/workaround
because the thread is eventually killed by exit(status) in ae-bridge.
Once we actually fix the ASDP bug, we will no longer call exit(..) and
the second-side effect will become apparent.
JNI: Fixed stale reference errors in input-android
cleanup: Remove unused method from CoreInterfaceNative.
bugfix: Fix for newer versions of Nyko Playpad controllers.

Fixes issue #106.

I hope this doesn't break the hack fix for older versions of this
controller.  The conditional using the device name is based only on my
own personal observations with the original version of this controller.
doc: Update changelog.
res: Updated translations.
doc: Update changelog.

Won't be seen by most users, but it's good to be historically accurate.
front: Added preference for each player's deadzone.

Can be persisted in custom profiles.  Built-in profiles and legacy
custom profiles default to 0% deadzone.

Closes Issue #121
doc: Updated changelog.
front: Encapsulate seekbar prompt for easy reuse.

Same code in two places, so refactored it into a common utility.
cleanup: Revise prompt method names for clarity, refresh javadoc.