Reorganize menus in KStars.

+ Created the "Data" menu and moved "Download New Data" (GHNS / KNS3)
and "Updates" (which provides options to update comet / asteroid /
supernova data) under it.

+ Moved the Observation Planner to the "Observation" menu.

+ Changed internal name of the Observation Menu from oal to
observation.

+ Indentation improvements