* AvInputStream
    * Rename setBufferred to activate.
    * Rename getBufferred to isActivated.
* InputFile
    * Rename readStream to activateStream.
    * Rename getReadStream to isStreamActivated.
* Update apps and pyTest.

Avoid warning messages when SWIG has access of these overload functions
(const).

Correctly set BigEndian, Alpha, and Planar flags.

* Error for subsampling YUV420 in init when fill in cumulSrcOffset.
* Use FFmpeg function av_image_fill_pointers instead of manage it in our
code.
* Remove unecessary _srcOffsets and _dstOffsets.

* Clean documentation.
* Move static method.
* Remove unecessary getProperties with parameter.