This expands upon the limited FromTemplates MultiBrush collection
shorthand:
- Adds a corresponding FromActors shorthand.
- Allows FromTemplates and FromActors to mix in additional properties,
such as weights and backing tiles.
- Updates the MultiBrush collections used across the official mods to
make use of these shorthands.
Note that this reorders some MultiBrush definitions for
conciseness. This partially (cosmetically) re-randomizes map generator
output.