Remove dead code in core

This pull request removes some dead code in core. The major changes are
* Remove some code which was commented out
* Remove ```PoreCore.LogErrorInGlobalMap()```
* Remove ```ProtoCore.ResetForDeltaExecution()```, ```ProtoCore.ResetDetalCompile()```
* Merge ```ProtoCore.ResetExecution()``` and ```ProtoCore.ResetForDeltaASTExecution()``` and rename it to ```ProtoCore.ResetForDeltaExecution()```
* Some other minor cleanups.

These dead functions were for old graph UI, so it is safe to remove them. 
Not really. I still want to add back the support for dynamic re-sharding of the VM, but it's a lot more involved than just this method. so it can go away for now.