Generalise validate_start_end_date to work on any datetimepicker pair.
Generalise validate_start_end_date to work on any datetimepicker pair.

dariusf/coursemology.org,allenwq/coursemology.org,dariusf/coursemology.org,nnamon/coursemology.org,nusedutech/coursemology.org,Coursemology/coursemology.org,allenwq/coursemology.org,nnamon/coursemology.org,dariusf/coursemology.org,allenwq/coursemology.org,nnamon/coursemology.org,allenwq/coursemology.org,nusedutech/coursemology.org,Coursemology/coursemology.org,allenwq/coursemology.org,dariusf/coursemology.org,nusedutech/coursemology.org,nnamon/coursemology.org,nnamon/coursemology.org,Coursemology/coursemology.org,Coursemology/coursemology.org,Coursemology/coursemology.org,dariusf/coursemology.org,nusedutech/coursemology.org,nusedutech/coursemology.org