add option to remap intensity colors

[unitycoder]

using gradient texture or values,
so that no need to use remap-texture in shader.
(although more flexible as a shader, could still add that shader also)

• checkbox for remap colors
• field for gradient texture
• remap 0-255 intensity using gradient values, into RGB

[unitycoder]

yeah, probably better to do in shader remap.. (use gradient shaders in the viewer).