Merge pull request #290 from afarra/master

Ability to change text brightness in night mode
fix bugs in transition between portrait and landscape on tablet.
fix a tablet crash, allow settings/help/etc to work in landscape.
brother Gharib Karim's Kurdish translation, updates to readme.
fixed directory name for Kurdish, updated translations, corrected brother Goran's name in credits for Kurdish.
Update README.md
minor bugfix for null on cleanup
initial tablet translation mode.
simplify code for translation task, and also fix translation header cut off.
Update strings.xml

Update Russian translation, fix some errors.
Update strings.xml

Editing name of Russian translator.
basic audio, highlighting, and page headers working when there are two visible arabic pages.
highlighting and unhighlighting changes
initial long press support for dual page mode. center pages in portrait.
Merge pull request #293 from Valey/patch-2

Update strings.xml
Merge pull request #294 from Valey/patch-3

Update strings.xml
support audio for page download mode on tablet. automatically decide tablet mode based on screen size instead of a constant.
fix bookmarks for dual page mode.
now can do operations on ayat in tablet mode. also did some moving of some files.
highlighting works for translations in tablet mode.