Make Society location nullable
Make Society location nullable

location will not be known when societies are initially created
Societies will be read from sheets of languages + iso codes, which do
not include lat/long data.  Lat/long data must be extracted from
society variables later (e.g. EA104, EA106).

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