For T7435, this...
* Adds a resource folder named preset_icon, which contains tool_icons and emblem_icons. These are filled with pngs.
* Adds a little dialog for loading and combining the above pngs into a preset icon, with some sliders to adjust the look of the tool icon.
{F5487490}
Things that need to be considered:
1. Do we want to create the folders for the icons in the user's resource directory too?
2. Maybe the grid for the tool icons should just have two side by side...
3. The last slider is actually a super-simple levels filter, how should we go about naming it properly?