Finished the delcaration of the Map class

This is actually a lot harder than I was expecting. When I program, I
approach from the angle of "What do I need to do?" rather than "how do I do
this?" At least this is finally done, so I can get to the implementation
stage. But, as I progress, I'll need to keep in mind what I need for the
index file.

Actually, I just realized that I didn't write the index functions. Well,
it should be interesting, at least.