Ignore Maven plugin files of ForgeModRenamer and ForgeJarCreator
Add modules to parent pom
Fix inheritance map

If a Minecraft class extended another Minecraft class, mods wouldn't be
able to call methods/fields in the parent Minecraft class.
.gitignore improvements

- Add child .gitignores to .gitignore (they're redundant, but my IDE
likes to add them)
- Add all files in the target directory to the .gitignore
Update to latest Forge