Modeless windows

[NeVeSpl]

That required more changes than I expected, but the final effect is quite nice. I hope that I have not broken any existing functionality.

[jeremytammik]

wow! this is the most exciting pull request ever. fraught with risk, of course. cool. thank you very much for this brilliant contribution. i'll try to take a careful look and test a bit before final integration into main codestream.

[jeremytammik]

i see one very apt comment:

		// TBD: For the Snoop.Data.ElementId object I need access to the current
		// document so I can retrieve the Element.  However, from the context of something
		// like a Parameter.AsElementId(), the Document is nowhere to be found.  So, hack
		// around it for now by letting original TestCmd set this value.  Its not local-enough
		// when browsing though, so it could be wrong if browsing doesn't stay within the 
		// original document! (jma - 05/03/05)

would it be easy to implement a warning message when the user (inadvertently) swaps to a different document?

easier than implementing the full solution?

[NeVeSpl]

I must admit I have not looked into CollectorExtElement and *Stream classes to check how they determine on which document they are working, but they definitely did not use static public Autodesk.Revit.DB.Document m_activeDoc = null; which was below that comment. I will look into that deeper, but after first a few clicks switching documents does not seem to cause any problems...

[NeVeSpl]

Indeed, there is a problem after switching to a different document, I will address that in the next PR.

[jeremytammik]

brilliant! Thank you very much for taking such a careful look!