Reduced model map node size to 32x32.

Reducing the node size required reexamination of the method listing
pixels overlapped by the entity since the Worker can now span up to
three in the X and Y directions for a total of nine.
Now matching map_node with tile. Interim check-in.
Added weights to non-zero terrain tile movement.
Comment out edge weight changes for now.
Merge branch 'issue17' into develop

Something weird is going on with the edge weights, and the workers
navigate the map inaccurately. Leave actual modification of the map
commented out for now.