+ Call the fake catalog for internet-resolved objects as
  "_Internet_Resolved". The prefix "_" has the dual purpose of making
  it look "internal", and making it appear at the end of the sorted
  list of catalog names in the settings dialog. The name is more
  meaningful to the user.

  Also, we hold this name in a string that is initialized in the
  constructor, as it is used in multiple places -- makes it easy to
  change, but we should refrain from doing so as it will result in a
  junk catalog remaining in the skycomponent database.

+ Allow enabling / disabling the "_Internet_Resolved" catalog like any
  other catalog in the settings dialog. This is different from
  enabling/disabling resolution, which is controlled by a checkbox
  below (introduced in one of the previous commits)