Different sized tiles

[terrill37]

Tiles currently fixed to 32x32 pixels. Potentially want to add ability to place larger (64x64) and smaller (16x16) tiles from different sets.

Things to consider:

• additional grid spacing for smaller tiles
• grid highlighting for larger tile spots
• selected tile chooses the bin highlighting size
• load different sized tiles in consistent manor
  • all tilesets sorted by size in different sheets