Core/maps.py: Added PlanetHistory.load() method.

Signed-off-by: Martin Stone <martin@d7415.co.uk>
parser.py: Fixed the News Scan parser to attach entries to the correct planet.

Signed-off-by: Martin Stone <martin@d7415.co.uk>
parser.py: Fixed the initial scan-planet link to use PlanetHistory.

Signed-off-by: Martin Stone <martin@d7415.co.uk>