fix SQLQuery: put directly integer value in update or insert, because else it won't work with boolean columns
fix SQLQuery: whereNotValue: use the null-safe operator
(cherry picked from commit 00dc4999441c28f85845f74b9432e46716ab7fdc)
Merge branch 'master' of https://github.com/passerellesnumeriques/Students-Database into dev
use AUTO_INCREMENT feature for applicant id
fix DB table creation: mark indexes as unique when all columns are unique