misc fixes

Geo::GTFS doesn't use anything from Geo::MapMaker.

Add "Type '$0 --help' for help." message.

List more commands in the --help.
add aliases to the Geo::GTFS module.  This way, other modules can access them.
more integration of aliases.
on second thought we're putting aliases in its own package
moving aliases to its own module
moving aliases to their own module