Added relationNames to objectHeader.

objectHeader now contains the names of the related objects.

getRelatingObjects returns the names of the objects relating to the
specified name.
Revised getAreaBase.

getAreaBase now uses getObjectData to load the areabase.
If a signal / signal group is specified all area bases will be loaded
and returned in a dictionary.
If only one area base exists the area base is returned.

The area bases are contained in the areaBase class containing the name
and the data.