Emacs scratch buffer implemented

[Brian T Rice]

I've added a scratch buffer specific to Slate now. It colorizes
expressions like a normal buffer, but doesn't save to a file, and you can
work with expression evaluation and such. "Ctrl-c w" (for "workspace")
activates it. This is really helpful for writing up little experiments
that you may want to throw away or keep, but don't want to decide up-front
about.

There's also a print-it function now, "Ctrl-c p", which is supposed to
evaluate the selection and print within the current buffer, but right now
it's not capturing the output from the REPL, so it's the same as Ctrl-c e.

-- 
Brian T. Rice
LOGOS Research and Development
http://tunes.org/~water/