Improve HSV tab in color wheel

[MathemanFlo]

Fixes https://github.com/armory3d/armortools/issues/1245

Basic idea: Store the color as hsv as well. Restore all hsv dependent things (hsv sliders and the color wheel) using the stored hsv color. If the rgb color changes, then update the hsv as well.

@luboslenco I was unsure whether the zui.Handle class should get new entries in order to fix the issue. Therefore I have abused existing fields which is somehow horrific. Please let me know how to improve.