Allow conversion of batched images and videos to matplotlib and back

Also adds opencvbgr_to_bob and bob_to_opencvbgr convenience functions.

changed milestone to %Bob 9.0.0

changed the description

Guys we have functions in bob.io.image to convert images between bob format, matplotlib format, and opencv format. Please use them!

Thanks for the MR @amohammadi,

Shall we bump Bob 8.1.0?

I think if you just release bob.io.image should be enough.

patch version?

patch in the changelog since I already changed the version here.

merged

mentioned in commit 77d31bbc