(This fix is really by Jeremy)

(This fix is really by Jeremy)

Here's my suggested replacement for gzip.py for 1.5.1.  I've
re-implemeted methods readline and readlines, added an _unread, and
tweaked read and _read.

I tried a more complicated buffer scheme for unread (using a list of
strings and string.join), but it was more complicated and slower.
This version is a lot faster than the current version and is still
pretty simple.