Blender Git Loki

Property Search: Refactor / simplify, and better layout

The single column layout works much better now, as most of the code that
dealt with trying to remove empty layouts has been rewritten. The search
filter code is not a completely separate pass for the sake of simplicity.

Also, toggle buttons have their text replaced with the rna property name.

There branch is far from stable, and there's a tricky memory leak still to
track down as well.