[Bf-animsys] Shape key editing enhancements

[Grigory Revzin]

Hi everyone!

A few days ago, I've been accepted into Blender's GSoС to develop a
significant update on the shape key editing workflow.

The update is planned to bring in
1) a new UI that makes browsing, comparing, and blending (adding or
interpreting shape keys) between shape keys much easier
2) proportional falloffs for Blend from Shape like here:
http://www.youtube.com/watch?v=274Do-PULb8
3) the editing now happens on a scratch shape key which is
automatically committed to the active shape key by default (exactly
how the current interface behaves), however, you can manually commit
it to another shape key (if you've edited the wrong one), compare it
with the
4) one will be able to edit the shape key on top of a mix (like now
with Apply Shape Keys in Edit Mode pressed), but the mix can be
independent from the existing animation

More details with UI sketches are situated here:
http://wiki.blender.org/index.php/User:Revzin#From_the_user.E2.80.99s_POV

The ideas for the update originated back when I was creating a
shapekey-based facial rig with around 150 shape keys for later use in
Source Filmmaker :)

I'll be happy to hear opinions and ideas about the proposed design.

Thanks,
- Grigory