Colormap Min/Max and save/restore state

[bourdaisj]

Description

Sometimes, restoring a state does not restore the colormap min/max values correctly.

Reproduce

• Load any dataset
• Change the color transfer function
• Take a look at the min/max values
• Hit 'Save State'
• Hit f5, and reload the previously generated state file
• Take a look at the min/max values, they should be different from the one at step 3

Expected behavior

The min/max values should remain the same after restore