with spaces in filename.

I changed the module to use string methods instead of the string
module.  Also, instead of stripping the last character of the filename
(assuming this is the linefeed), I strip trailing whitespace (assuming
creating files with trailing whitespace in their name cannot possibly
be a wise idea).

(Note that I believe that /F's "workaround for broken uuencoders" is
no longer needed since the recent fix to binascii.c, but I'll leave it
in since it appears pretty harmless.)