[Bf-python] Write access to Shape key data (wrapped data)

[Ken Hughes]

One or two bug reports are related to not being able to edit shape key 
data for meshes.  Same problem probably exists for lattices and curves. 
  A quick fix would be to add an attribute to the KeyBlock API which 
wraps the coordinate data stored in the datablock.  I've tried this with 
a mesh and it works OK.

My first thought was to tackle this through the Mesh API, but the stored 
data for each shape key is only the vertex coordinates; none of the 
normal, UV, etc., info is stored.  So it would be hard (but not 
impossible) to "fake" these as MVerts.  Same would apply for curves and 
lattices.  Does anyone have any ideas?

Ken