Restructure the asset/resource tree

[ravepossum]

SImilar to #291, we should re-evaluate how the res/ folder's contents are organized.

Some initial questions to consider are:

• Is res/ the most appropriate name?
• Should data (e.g. encounters) and graphics (e.g. UI elements) remain intermingled, or be separated out?
• Is it useful to have a generic graphics/ folder or should everything just be organized conceptually?
• Where should map models, textures, etc. live when they're dumped?

[lhearachel]

Codifying my thoughts here.

• Is res/ the most appropriate name?

I think that it is fine, but probably not the best. assets may be more clear.

• Should data (e.g. encounters) and graphics (e.g. UI elements) remain intermingled, or be separated out?

I like the intermingled structure that we have, but I think that we should adopt a rule that data and graphics cannot be used as standalone names for folders in the tree. This should alleviate potential confusion points. Where it gets tricky is something like overworlds; some belong to trainers, so would those be under field/overworlds/ or trainers/...?

• Is it useful to have a generic graphics/ folder or should everything just be organized conceptually?

Under the above rule, I would change the name of the current generic graphics folder to interface (since it's not just applications, as it includes message boxes and the like).

• Where should map models, textures, etc. live when they're dumped?

field/maps.