[PATCH] Update help text for commands implemented in Python

[Tom Tromey]

>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:

Tom> Philippe pointed out that the "enable frame-filter" help text looked
Tom> funny.

Tom> While fixing this I noticed a few more problems in the help text of
Tom> commands written in Python:

Tom> * Trailing newlines
Tom> * Wrong style for metasyntactic variables
Tom> * Indentation of the text
Tom> * ... and finally, I thought the function usage lines didn't need
Tom>   that extra newline -- someday I'd like to be able to write a
Tom>   "usage" command that just greps for the Usage line, so ideally it
Tom>   would be tighter than what was done here

Tom> This patch fixes all the problems I noticed.

I'm checking this in now.

Tom