Adding and removing entries - some improvements

Added UI buttons for adding and removing entries.

Newly added entries will use the color of the currently selected entry, if no entries are selected then it will use the color picker's current color. This way you can add an entry with any color you want, without having to first create it then select it to change its color.

Newly added entries will be placed in front of the currently selected entry, if no entries are selected then it will be placed at the end of the palette.

Newly added entries will now be selected upon creation.

Palette info text will now correctly update when adding and removing entries.

Fixes to ensure palette data is properly updated when adding and removing entries.