From commit dd74a851, to be exact. Now cap_ffmpeg.cpp should actually
build if HAVE_FFMPEG is true.

Also modified some gpu sources in a similar manner.

for libpng added.

Set and Get methods are not implemented;
Camera based video capture is broken due to modifications.

TIFF build was fixed;
Direct Show back-end was enabled;
More accurate guards implemented.

GPU module turned off;
TIFF support turned off;
Windows Managment and Video IO (VFW) turned off.

This reverts commit 4abf0b31.

Changes are reverted because they break build of proxy dlls on Windows

get back to single-version ffmpeg wrapper (no more v2); make sure the library builds and the tests pass on Ubuntu 10.04 that includes pretty old version of ffmpeg

added version number to opencv_ffmpeg dlls (it's added only when dll copied to the bin directory); it resolves #1827

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