added watch object handling for Revit
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into MVVM

Conflicts:
	src/DynamoCore/ViewModels/DynamoViewModel.cs
	src/DynamoRevit/ViewModel/RevitWatchHandler.cs
Fix MAGN-4095 Getting crash while running Document after closing and reopening again.
Implemented a new "TimeStamp" struct for time keeping.
Merge branch 'Concurrent' into TimeStamp
Replaced "long" with "TimeStamp" struct that carries "TickCount"
Implemented "TimeStamp.Equals/GetHashCode" methods, updated test cases.
Merge branch 'Concurrent' into TimeStamp
Merge branch 'Concurrent' into TimeStamp
Moved "TimeStamp" class into a new file "TimeStampGenerator.cs"
Merge branch 'TimeStamp' into Concurrent
Moved test elsewhere and removed file "TimeStampOrderingTests.cs"
Include the import path in debug cores
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into testcaseupdate
Merge pull request #2173 from Benglin/master

Removed "Mixed Platform" from solution (and a build fix).
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into Concurrent
PNG version
Update to fix incorrect static error for a dynamic dependency
Merge pull request #2124 from Steell/revit-watch-fix

Fixed watch node on top of Revit: MAGN-4102
Merge pull request #2112 from Randy-Ma/magn-4095

Fix MAGN-4095 Getting crash while running Document after closing and reopening again.