Memory leak in color-blob-detection sample fixed;
Default face size in face-detection is set to 20%;
Error handling improved;
Some possible mat leak fixed;
Manager verison and engine interface version incremented to fix incompatibilities;
Docs updated;

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)