[Android] Use a HashMap in PrefsFragment.java instead of two CharSequence arrays.

This way, we hold the [key|value] pairs together in one object and reduce overall code clutter.
[Android] Multi-language support (or at least the basic foundation of it).

Added an example translation (Japanese). So now the Android version can both display in English and Japanese, depending on what the Android device's system language is set to.

Also did a tiny clean-up of InputConfigItem.java so that the parameters are slightly more descriptive.

Now, to do a translation in [x] language, all you have to do is take the normal English strings.xml and translate the XML entries into said language, and simply make a folder in the /res/ sub-directory in the form of values-[region code]. IE) With the Japanese translation, it is in the folder /res/values-ja

No configuration other than that is needed. After doing the above, the language should load fine on any device when set to that specific system language.

By default, if a translation file does not exist for a given system language. The app will automatically fall back to using the English translation.

This *should* be bug-free since I did check everything multiple times. But if any issues occur, please report them so that I can fix them.
[Android] Change the name of a variable in FolderBrowser.java to better reflect its purpose

Compressed file formats are not valid, so it's best to rename this to invalidExts.
[Android] Clean up the function CopyAsset in DolphinEmulator.java.

[streamtype].flush() is called when [streamtype].close() is called.

No need to null the references either after calling close(), the garbage collection will take care of it.
Simplify asset copying code a little bit in DolphinEmulator.java

Since the directories are already cached (with smaller variable names), use these instead so we can shorten the length of each line.
[Android] Some tiny cleanups in DolphinEmulator.java

- Join variable declaration and assignments in function onTouchEvent()
- Change a for-loop into a foreach loop in dispatchGenericMotionEvent(). Makes the loop body a single statement.
[Android] Clean up function SupportsGLES3 in PrefsFragment.java a little bit.
[Android] Integer.toString isn't required in this string declaration. Concatenation handles this.

For example: "string" + 1 will just be concatenated as "string1" implicitly.
[Android] Add translatable="false" to the names of the string arrays in prefvalues.xml.
[Android] Make the file browser look much more nice and user friendly to use.

This is what it now looks like: http://i.imgur.com/KOZgA1i.png

As usual, if any bugs arise from this rather large change. Please report it so I can fix it.
[Android] Main title text for the file browser items are bolded again. Must have removed it accidentally during the previous large refactor.
Fix invalid C++ code (returning reference to local) - thanks devm33.