• Installation system where a resource pack will be stored with the mod and be unpacked into the resource packs folder on load (if it's not already in the folder, and if it isn't disabled by the config).
• The retexture will be default for the mod, while the old textures will be the internal resource pack.
• Two programmer art variants: Programmer Art 1.2.5 and Programmer Art b1.7.3
• Programmer Art 1.2.5 will have the current variants of textures.
• Programmer Art b1.7.3 will have older variants of textures, old Aercloud colors (I have these sitting on my desktop somewhere -bconlon), and a rename of the Altar to Enchanter in the language file.

https://github.com/MinecraftForge/MinecraftForge/blob/eb1a9b57c6cc4d5cb4ad3c4305c2a73015d28917/src/test/java/net/minecraftforge/debug/AddPackFinderEventTest.java
https://github.com/TeamTwilight/twilightforest/blob/33b5529d64cdb017c51aa10c6932d6a646eced94/src/main/java/twilightforest/TwilightForestMod.java#L147