Remove non-existent tilesets from label comments and alphabetize

[GriffinRichards]

Reverts changes from when this file had been synced with some old, odd behaviors from Porymap, namely that

• The sections are mostly, but not entirely, in alphabetical order (it's now entirely alphabetical)
• It includes sections referring to tileset names that don't exist (the associated labels are now put at the end, under an "Other" section)