New version attached. Coding-style should be fixed, and hopefully this
will not be word-wrapped.
There were some bugs with NULL as the user in symbol_(get|put), that should
be fixed now.
I've added an error message for when a module tries to symbol_put() a
module that it's not using. This should keep the putted module's ref count
from being set to -1, which is what happens now. It should also make it a
lot easier to track down where the extra symbol_put()s are comming from.