Blender Git Loki

* Replaced the three X/Y/Z sliders that controlled the texture size in sculpt
mode with a single slider. (Doesn't seem likely the user is going to want to
scale in one axis differently from another.) Additionally, the new slider
works correctly in Tile mode in addition to 3D mode. In Tile mode, the slider
value is considered pixel units.

In the process, found and fixed a few sculptmode bugs
* When loading a file that is already in sculptmode, initialize sculptdata
as soon as the first sculpt/partial-visibility operation occurs
* Bug in the undo_push code; reading from free'd memory