Blender Git Loki

Sculpt: smothing ops now slide UVs

* Wrote a new function, SCULPT_reproject_cdata,
to reproject loop customdata after smoothing.
* SCULPT_reproject_cdata is only called if UV
layers exist.
* All of the smoothing tools (hopefully all)
use it.
* This change is necassary to properly support vector
displacement maps in the future; otherwise DynTopo
will introduce lots of noise into the uv tangent
space.