[vtkusers] bug/fix with vtkLookupTable (ver 3.2)

[Jiro Inoue]

There is a problem with vtkLookupTable::MapValue() which causes the
incorrect color to be mapped to a scalar.

The quick fix for direct mapping of integer values is to change:

LINE 245:
	float scale = this->NumberOfColors/(this->TableRange[1]+shift);

TO:
	float scale = 1;


The intent for non-integers is not clear to me though... (should input of
0.6 be color #0 or #1? etc)

-Jiro