Objective Highlighting

Quick update: Objectives (carrots, and once you've gotten them all, the burrow) are highlighted by hovering the mouse over the carrot count area.

Also, fixed two rare (single report) bugs; a crash bug if an enemy doesn't generate a path, and a bug where objectives can appear partially behind other terrain if that terrain used to be a carrot in a previous playthrough of the same session.

EDIT: Now also added a paint-style font