After internal discussion, it was decided that we need to include
"contributors" to the license header. This avoids claiming that the
Java source files are under the exclusive copyright ownership of Forge
LLC, which excludes contributors that still hold copyright ownership
over their contributions (but is licensed under the LGPLv2.1 as stated
in the Forge CLA).
Convert Forge to use Official mappings.
Mojang released their obfuscation mappings but we have not used them up until now due to wanting to get their license to be more explicitly permissive.
It is clear that their intent is to allow us to use their names for developing mods like this.
See the full wording, and our interpretation here: https://github.com/MinecraftForge/MCPConfig/blob/master/Mojang.md
Fix not including userdev source in sources jar.
Update license header of files that need it.
Delete patches_old folders. Most are unneeded in 1.13+ as the systems they effected were changed significantly. Any that need to be readdressed can be done as PRs.