Moved the core event handler parts to FML. Implemented the Forge network handler based on the new
netty strategy.

Updated FML:
MinecraftForge/FML@3b2994a3def35a2d3058960b71dc59dc48b802f9 Some patching touchups
MinecraftForge/FML@557357fe179529e0b44aab2f3fcef0c5adf981d5 Update for log4j2
MinecraftForge/FML@a2b324beb2ef6ec73000678c9305fd70d4ec1643 Copy eventhandler from Forge into FML. It is going to replace a lot of the runtime event systems.
MinecraftForge/FML@4071ff38afe15fddf5db0be882f5627f503a37c6 Patch some GUIs. We're gonna add some basic mod gui config support.
MinecraftForge/FML@0b419ac79c307579f162d47e0388a9d75bcd0a6e Fire a user event down the channels when a handshake has occured.