added support for saving data in the database. Added cf zone index to database. Now need to fix all exceptions

added some way of saving data. need to remove everything from remote database and update it with new data. Some problems when we click save in DB. crash

already reading DB. Problem: what do we do with the data? We should create the necessary crazyfly zones, in the exact position?

Rework in CFZones. When we remove now, everything OK, we unlink perfectly, we dont change the names... Getting some crashes when we close tabs. Need to fix

restructuration in LINKER. Need to see if everything goes OK. Need to unlink, need to remove options, etc..

Added table. Need to take care of everything else, like unlink, impossible to add same student id twice, remove added elements from choices....

added table, added linker. Need to rework a bit the linker, and to fill the table with the linker. Also, unlink