This unifies the settings APIs.
This also unifies the sync and async registration APIs, since the async
registration API did not support adding non-functions to the API table.
- Use local variables for tabs in place of globals
- Merge together if statements where possible
- Replace manual table searching code with indexof where possible
Change the name for texture pack description files from "info.txt" to "description.txt" in order to keep the naming consistent between description files for both mods and texture packs.
Also add backwards compatibility for texture packs that use "info.txt", and note in the log that "info.txt" is depreciated.
