Removed SWIG from Android toolchain; always search for python; find_program/find_package cmake functions wrapped for case of cross-compiling.

temporarily reverted to FLANN 1.5 (FLANN 1.6 is put to a separate branch FLANN_1.6 until it's stabilized)

fixed positioning in ffmpeg wrapper (thanks to mike_at_nrec for the patch). Added frame positioning feature to laplace demo to test the feature

fixed positioning in ffmpeg wrapper (thanks to mike_at_nrec for the patch). Added frame positioning feature to laplace demo to test the feature

added square_size cmd line param for calibrate.py
added _coverage.py script to compute cv2 api coverage by samples (just for interest, may be removed later)