Undo commit 3340. Let's standardize names of non-core files to only have
dashes. That's also consistent with the edit/ and sandbox/ apps. Mu
programmers will tend to pervasively use dashes, just like Lisp
programmers.
Scripts will continue to use underscores..
Rename files to be consistent with my (forgotten) convention of always
using underscores over hyphens.
I'll leave server-socket.mu alone for now, since Stephen's hacking on
it.
Kartik K. Agaram