added proxy model for displaying observations and readings in the feature data dialog.
readings are now seperated by their type. only one type can be displayed at one time.
added the column names for readings and observations to the guiConfiguration class so all changes in the columns only have to be done there.
bugfix geometry, where reading types have not been saved correctly.
bugfix pseudotracker measure cartesian.
#86
added more attributes for different reading types to reading model, and GUIConfiguration class.
bugfix sensorcontrol, cartesian observations were not created correctly.
changed front sight/ back sight variable in reading that displays the sight of the reading measurement and removed from measurement config.
changed pseudotracker. the plugin now has to set the face orientation of the reading at the measurement.
closes #86
small bugfixes. #86