mainlining oskit-mach

The gnumach-1.3 release is out.  I'd like to merge oskit-branch into the
trunk now.  Any objections?

That is, make a gnumach-1-branch based at the existing gnumach-release-1-3
tag, which will be used for any more bug fixes, and then make the trunk of
the tree more or less identical to what the head of oskit-branch is now.
I think the makefiles might be in a somewhat hacky state and I might do
some random cleanup of that in the merge, and the changelogs will move around.

The main motivation for doing this right away is so I can put the Alpha
port into oskit-mach and do it just once without the stress on the
repository and the weirdness in the history you get from adding
subdirectories and files on a branch and then on the trunk later.