Reordered modules in Makefile to fix linking.

In the `MODULES' list, each module needs to be to the left of all
modules it depends on, in order to link properly. I had it in the
reverse order o_O!
Added `mem_Pool', a memory pool implementation.
Added the `map' module, along w/ the `map_t' type.

`map_t' is a quadtree which holds a sparse map representation. It
is designed to allow large winding map layouts which are not
necessarily rectangular in nature.