Add code_number field and method to read it
Add code_number field and method to read it

Fixes #11

shh-dlce/dplace,NESCent/dplace,stefelisabeth/dplace,stefelisabeth/dplace,shh-dlce/dplace,stefelisabeth/dplace,D-PLACE/dplace,D-PLACE/dplace,shh-dlce/dplace,NESCent/dplace,stefelisabeth/dplace,NESCent/dplace,shh-dlce/dplace,NESCent/dplace,D-PLACE/dplace,D-PLACE/dplace