Tile highlight color for tools should be defined by the pakset, not the theme

[Nazalassa]

When a tool is selected, the tile on which it would apply is highlighted in a certain color. This color is, if I understood correctly, defined by the theme (the option is named 'cursor_overlay_color'). However, the 'tile borders' (the lines that appear at the border of the highlighted tile) are defined by the pakset as images. As shown in the following image, it may happen that the pakset and the theme disagree, producing not-very-pretty results:



Thus I think the tile highlight color should be defined by the pakset (or the tile borders by the theme, but that may be more difficult, considering the pak size is not constant across paksets) so that the result does not look weird.

Actually, I think that since everything that is displayed on the map is defined by the pakset, the highlight colors that would apply to elements of the map should be defined by the pakset, rather than the theme. (after all, the theme is only supposed to define the interface, not the map, isn't it?)

[Yona-TYT]

I had suggested a while ago the idea of a default theme per pakset.

- So every time the pakset is loaded it will start with its default theme (if it exists in its directory), otherwise the one chosen by the user will be used.

- In the pakset selection window a checkbox ☑️ will serve to decide whether to use the pakset's default theme or if the one defined by the user is used instead.

So this would solve all these problems with themes in certain paksets.