UI update - Fix for heels poses & misc (Patreon)

Heels poses weren't working correctly for newer models because of latest changes to IK system. It's fixed now.

Also booleans for custom properties are now named on/off to make it clearer.

UI version is 2.1.35

Download Here

On other news I'm working on the next model which should be done by the end of the week. Then I'll start the poll's winner.