New decompile-free faster build process

Adds a new and improved (but experimental) build process as discussed with @AbrarSyed on IRC earlier (just missed you on #minecraftforge today). Removes the need for MCP, decompilation, and excessive recompilation – in favor of a brand new SpecialSource-based remapper currently executed via Maven.

Builds FE in ~7 seconds on my system.

Known issues:

* Localizations are not added (need to find out how to pull from https://github.com/ForgeEssentials/FELocalizations?)
* Versions not substituted in resources (should be easy with resource filtering)
* Client is not compiled (separate project? subproject?)

However, it does produce a usable build (run with 'mvn initialize' then 'mvn package', mod will be in target/). Again it is still experimental, but if FE wants to try it out.. :) Probably needs further testing before pulling.