Merge pull request #1 from neuecc/master

Update from neuecc
Merge pull request #2 from neuecc/master

Update from neuecc, more MainThreadDispatcher stuff
Using EditorPrefs to store AboutToStart state. Throw Exception when attempting to initialize MainThreadDispatcher from worker thread. Demonstrated in WorkerThreadTest scene. Added .meta file for MainThreadDispatcher with negative ExecutionOrder.
Undone b548ee6 to fix editor scripts looking for destroyed MainThreadDispatcher.
executionOrder was committed with default value, changed to -200
Fixed wrong .meta file exception in .gitignore

MainThreadScheduler.cs.meta was accidentally added instead of the
intended MainThreadDispatcher.cs.meta.
Added .meta files for missing scripts in scenes
MainThreadDispatcher removal handling moved to OnDestroy from OnApplicationQuit
Added scene explaining multiple MainThreadDispatchers handling
Added IntervalTest
InstanceName will now throw exception when MainThreadDispatcher is not initialized.
Cull Excess Dispatchers
Added LoadLevel test
Added DontDestroyOnLoad to Awake. Add Dispatcher Culling Mode.
Adapted example scenes to show and toggle Dispatcher Culling Mode.
Polished tests a bit
Renamed test.unity scene and related scripts, added namespaces
Removed CheckForMainThread(), replaced with try/catch in Initialize()