Loading of Tiled JSON export
Almost done

Only needs

1. point inclusion for polygon
2. `blocked?` using 1
3. `at` using 1
Tilemap sufficiently offline tested

Interactive testing will follow
Added tilemap support

They said it was impossible. They said I shouldn't try. They called me
mad for doing so. *MAD I TELL YOU*! But I showed them. I showed them
all!