Py-xbrl

Fixes 47 and 48.
Improves mapping between concepts and labels.

Implemented solution for 39.

Implemented solution for 11.

Fixed issue 30

Renamed package from "xbrl_parser" to "xbrl" as discussed in 24.
Implemented multiple minor improvements.

This release introduces breaking changes!!
Please change your import statements from
python
from xbrl_parser.instance import parse_ixbrl_url

to
python
from xbrl.instance import parse_ixbrl_url