Add DoubleClickButton for category deletion.

The double click button only takes effect after the second click. This
will prevent the accident click on the dangerous buttons without making
the UI ugly.
Add Arabic to the locale list.  Do not display warning for the TTS extended
or ESpeak since they are deprecated.
Display warning if the locale is not available for the current TTS engine.
Rus translation update
Use SA for Arabic TTS country code.
Only display TTS language not available warning once.
Sync Italian translation
Limit the landscape buttons layout to tablet devices only.