Store how beam is applied
Created by: aroffringa
Adds the columns LOFAR_APPLIED_BEAM_DIR and LOFAR_APPLIED_BEAM_MODE to the field table. Rerunning applybeam on a measurement set will now result in an error (if necessary, later it could be made possible to undo the beam-application and remove the keywords, or even to change it from one direction to another). Ticket #60 (closed) .