[Bf-interface] Widgets Testing

[Julian Eisel]

Hi all,

For the past days, I've been working on the widgets project again,
mainly working on a 'new' transform manipulator that uses the new
widget system and has some new features. I'd consider this as mostly
finished now, so it seems like a good time for some feedback/testing
:)
Also removed some UserPref options for the manipulator which I found
unnecessary, would be good to hear some opinions on that, too.

I've merged the wiggly-widgets branch into UI-experiments, so it can
be tested in both.

Screenshots:
https://developer.blender.org/F228183
https://developer.blender.org/F228184

Greetings,
- Julian -