This is not pleasant to read (and much, much less pleasant to write!) but
sort of necessary in an open project. Right now it's quite hard to figure
out what is licensed how, which doesn't matter much to most people but can
suddenly become very important when people want to know what they're being
allowed to do.
I kept the notices as short as I could. As far as I could see, everything
without a clear license notice is LGPL v2.1 or later.
This is lint reported by the new lint-checking functionality in beautify.py.
(We can change to a different lint checker if we have a better one, but it
would probably still flag these same problems.)
Lint checking can help a lot, but only if we get the lint under control.
