Add xml files for each line (copied from another directory in tree).

Allows easier loading of which lines a station is on.
Allow station class to be on multiple lines.

Station class now uses list of lines instead of a single one.
set_line method resets lines to only the list that is passed.
add_line adds a single line (only if not already in list).
get_line returns a list instead of a sting.
Update docstrings of methods to set/get lines.