Post-jam changes

Some tweaks after the jam is over:

- Content: Added a new level and minor changes to three existing levels, to smooth out the difficulty curve.

- Content: Better resolution when two characters attempt to move into the same space. The conflict is now resolved by which colour tile they're on: whoever is on their own territory gets priority.

- Bugfix: Removed a duplicated level.

- Bugfix: Corrected my name on the main menu.