Add release notes for #3608, #3861 and #3886

[hugovk]

No description provided.

[olt]

Here is a snippet for the release notes for #3886, to avoid further last minute merge conflicts.

Image quality for JPEG compressed TIFF 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The TIFF encoder accepts a ``quality`` parameter for ``jpeg`` compressed TIFF files.
A value from 0 (worst) to 100 (best) controls the image quality, similar to the JPEG encoder. The default is 75. Example:``im.save("out.tif", compression="jpeg", quality=85)``

[hugovk]

Thanks! I'll add it to this PR.

[hugovk]

Added!

[hugovk]

Azure Pipelines passes. Not going to wait for Travis CI or AppVeyor to merge for this one.