added key frame handling to ffmpeg wrappers

minor refactoring of gpu tests

#1713 Added the possibility of setting user_block_size manually for gpu::matchTemplate function (and gpu::convolve). Added a buffer param into these functions. Removed using of 2^n block sizes when it's not necessary.

added more tests for gpu cvtColor
fixed RGB->YUV conversion

disabled NVidia Visualization test, it's functionality (draw rectangles) doesn't used in gpu module

moved TargerArchs and DeviceInfo to core
fixed bug in GpuMat::copy with mask (incorrect index in function tab)

used random images in gpu filter tests

added assertion on double types for old devices

changed epsilon for matrix comparison in gpu::sqrt test

added additional tests for gpu filters
fixed gpu features2D tests

fixed some bugs in gpu module

refactored tests for them

fixed several warnings

lot's of changes; nonfree & photo modules added; SIFT & SURF -> nonfree module; Inpainting -> photo; refactored features2d (ORB is still failing tests), optimized brute-force matcher and made it non-template.