fix warning on download update service
(cherry picked from commit f8f04ae26de02e809701a19bfe71f182470d6f2f)
when choosing a subject, keep the filter of group/batch
fix locks: special lock for insert. really lock everything during remove
lock only requested rows on update
remove javascript error when page unloaded before loading is complete
Merge branch 'master' of https://github.com/passerellesnumeriques/Students-Database into dev

Conflicts:
	www/component/Page.inc
	www/version