Made EndpointAddress virtual

Trying again to make EndpointAddress virtual.  Sorry, there's still some differences in line endings or something.  I tried for 20 min to get rid of them and show only the one line change, but I just don't know Git well enough.  I can just log a bug instead if that's easier, or we can build our own custom version for our purposes.
I haven't a clue why Git does this.  I have it set to preserve line endings and tried from both Windows and the GitHub editor.