+ Implements a put_nowait method.
+ Adds a corresponding Queue.Full exception.
+ Simplifies the implementation by adding optional "block" args to get() and
put(), and makes the old get_nowait() and new put_nowait() one-line
redirections to get() and put().
+ Uses (much) simpler logic for the nowait cases.
+ Regularizes the doc strings to something closer to "Guido style" <wink>.
+ Converts two stray tabs into spaces.
+ Removes confusing verbiage about the queue "not being available" from the
docstrings -- never knew what that meant as a user, and after digging into
the implementation still didn't know what it was trying to say.