Add parse location fields to NullTest and BooleanTest structs.

 Add parse location fields to NullTest and BooleanTest structs.
 
 We did not need a location tag on NullTest or BooleanTest before, because
 no error messages referred directly to their locations.  That's planned
 to change though, so add these fields in a separate housekeeping commit.
 
 Catversion bump because stored rules may change.