\withsubitem{}: New macro. Change indexsubitem temporarily for another

\withsubitem{}:  New macro.  Change indexsubitem temporarily for another
	macro.  Intended usage:

		\withsubitem{(in module foo)}{\ttindex{myfunc()}}

	This allows indexing functions from other modules/class/whatnot
	without being dependent on the exact expansions of several macros
	internal to python.sty.  It's also easier to read in the source!

Some new "logical" macros that seem to be useful:

\regexp{}:  For regular expressions.  To make it easier to keep the appearance
	consistent.

\mimetype{}:  Don't use \code{}!

\envvar{}:  Environment variable.  This does some indexing as well.

\character{}:  Just a character we want to talk about in the text, but not
	a Python constant.