Remove all warnings, deprecated methods from RevitNodes

### Changes 

This PR removes all build warnings and all Revit API deprecated methods from RevitNodes.

This PR also removes all usages of the deprecated `DocumentManager.DeleteElement(ElementId)` from RevitNodes.  As such, this PR also removes those deprecated methods from DocumentManager (the third commit) to reduce any further confusion / maintenance of deprecated code.

### Unit tests

No new unit tests as essentially no new functionality was added.  

@lukechurch
What's the intention for hiding the existing names here?