Use new frame dropping code from upcoming libde265 0.7.
For now either drop all frames if too many late frames are present, or drop none if decoding is fast enough.
Removed support for compiling against libde265 < 0.7
Updated dependencies to libde265 >= 0.7
Updated module check to search for libde265 >= 0.7
Support direct rendering.
Starting with libde265 0.7, the images can be decoded into application-created buffers to avoid data copying.
Add comments to functions.
Increase internal width to match required alignment for direct rendering.
Also disable SAO/deblocking when dropping frames.