Add helper methods for creating and finding method and field nodes#63

Jonathing wants to merge 3 commits intoMinecraftForge:masterMinecraftForge/CoreMods:masterfrom

Jonathing:feat/jonathing/master/creating-new-nodesJonathing/Forge-JS-CoreMods:feat/jonathing/master/creating-new-nodesCopy head branch name to clipboard