Remove a debug print.
Remove a debug print.
Remove one more debug print.
Add null checks.

Avoid attempting to load trace data if the engine controller is null.
Do not run the expression when shutting down.
Cleanup unused using statements.
Initialize the materials manager.

On Dynamo start and view activation.
Merge remote-tracking branch 'origin/Revit2015' into MAGN_4173

Conflicts:
	src/DynamoCore/Models/DynamoModel.cs
Merge pull request #2259 from DynamoDS/MAGN_4173

Magn 4173