add a new function abssum
fix the bug of test and perf because someone remove non-free module from cmakelist.txt

Some unification done to simplify camera switching.

Some code refactoring done.

Rair hangs on library installation fixed.

made it to give more verbose errors when arguments of wrong types are passed, added setters with types (e.g. setInt, etc)

Frame format setter added to both views.

Old Android support added;
Android 4.1.x fixes added;
Thead sync added;
Camera errors handling added.