Highlight changes in saved palettes are lost if a palette with highlights disabled are selected first

[ark-royal-91]

Repro steps:

1. Save a palette with highlights enabled, no hair color change selected, highlight changes enabled, and the highlight color changed.
2. Save another palette with highlights disabled.
3. Select the palette with highlights disabled in Saved Palettes, and then select the palette with saved highlight changes.

Result:
The palette with saved highlight changes will have all highlight changes reset.

Note: This is probably related to #12 - if hair color is selected, highlight information will save. Heterochromia exhibits the same issue - if only right eye information is saved, then selecting a non-heterochrome palette and returning will erase all saved right eye information unless left eye has also been set.