Reorganize source and solutions

[GoogleCodeExporter]

Our current src/tools division doesn't work terribly cleanly.

I'm going to change to have *all* the source with src, but have multiple 
solution files which include different (overlapping) projects based on 
intention.

This will temporarily break continuous integration until I've got everything 
working, of course.

Original issue reported on code.google.com by jonathan.skeet on 19 Apr 2013 at 12:55