[MonoDevelop] Installing MD 1.9

[Chris Wright]

This is a problem that I experienced and solved.

I tried using MonoDevelop 2 alpha 1, and also the latest copy from
trunk. I kept getting errors about MD being unable to load the addin
MonoDevelop.DesignerSupport, as well as a number of other addins; and
as a result, MD couldn't open any files to edit.

I had installed to /usr/local and had an existing MD1 install in /usr.
It looks like MD was looking for some addins in /usr/local and some in
/usr. Removing MD1 and installing to /usr made everything work.

If other people experience the same, perhaps this could be added to
the release notes.

Happy coding!