Fix version number in setup.py

Oops, I forgot to bump the version number in setup.py! This causes builds to fail.

Last release before Dear ImGUI branch

This release contains a lot of changes and fixes; see the file doc/ANNOUNCE-0.07 for details.

v0.7 will be the last release before work begins on the Dear ImGUI port. I don't plan to work on the Clutter backend any more than I have to, but it will still be available at least through the next release.

Release candidate 2 for v0.7

Fixes bugs in LV2 save/load handling, include paths on build, and more.

Release candidate 1 for v0.7

v0.7 is the first new release of MFP in a few years. I am pushing this release candidate in hopes of getting some QA from interested folks.