Cv headers soname

[kwizart]

Here are two patches used by the fedora package.

Fix opencv headers compatible with opencv2+ including OpenCV4 that has dropped support for opencv/cv.h

There is also an issue with the SONAME that integrate the micro version whereas the ABI is compatible with the previous libfreenect 0.5.0. So keep using libfreenect.so.0 instead.

[piedar]

Nice! I think it would be ideal to have both versions as symlinks, like libfreenect.so -> libfreenect.so.0 -> libfreenect.so.0.6 -> libfreenect.so.0.6.0 but I don't see how to do that with cmake. If you know a better way please advise - otherwise I'll go ahead and merge this.

[kwizart]

The symlinks are only useful for the unversioned .so to allow the linker to find the appropriate library at link time. It will detect the internal name of the library (SONAME) that also need to have a symlink or it will be created by the system linker at library registration anyway (ldconfig).

Others symlinks are not useful to anything and additional symlinks are usually not done across projects (looking at /usr/lib64/)