Module for generating different map types

[sgreenbury]

An interface for generating maps with different properties can be implemented. Current maps:

• Random
• Resources in corners
• River but these are loaded from file and a module with a trait defining the generation interface and some example structs that can be flexibly instantiated (e.g. with proportions of resources as arguments, dimension of map etc) would be better.

[edchapman88]

An idea to make generating new maps with non-uniform structure:

• Write a module to parse an (n,n) dimensional png as a map layout.
• Assign a colour for each map item (eg. food = (255,0,0), water = (0,0,255) ).
• An online pixel art generator, like this one, can be easily used to create larger, more complex maps, with an easy GUI that we don't have to implement.