GB struct member data

[stag019]

GB struct member data

[stag019]

I've nearly completed writing it.

Pros:

1. It works correctly.
2. It doesn't rely on a separate transpose_tiles() function.
3. It, again, will make implementing trim and mapfile easier.

Cons:

1. It's more complicated looking.
2. It takes twice as long. (around 10 seconds per 25000 iterations as opposed to 5 seconds).

I'm assuming con 2 isn't that big of a deal, but con 1... it may or may not be worth it. Once I master the code, I'll make a branch with it, and then we can decide on whether to merge it or abandon it.