The old MapDataArrayTGoMultiTexture relied on
being able to lock dowwn a specific texture unit
which cannot be guaranteed as external code
or render passes may bne uising that texture unit.

Instead we support the method having the name of a texture
along with the matching ethod in vtkProperty to name
a texture. Between these two users can assign texture
coordinate arrays to specific textures.

Deprecated the old index and unit based methods.
Removed a no longer needed vtkTexture.h include
which may bite some folks who are using vtkTexture
but not including the header (which they shoudl do)