Version 4.6 - Security and Functionality Upgrade

[TimDaniel]

Changes in this version:

Enhanced security - various enhancements to security.
Messaging - Administrators can now disable Simplegradebook messaging in their School Settings. Applies to Simplegradebook Pro schools only.
Attendance - Pro school Administrators can view detailed attendance in the student information display.  Applies to Simplegradebook Pro schools only.
Referrals - The ability to generate referrals and share them with administrators has been removed due to lack of use.  It can be re-instated on request.
Bug Fix - Grades including a "+" or "-" (eg. B+) can now be entered as override grades in letter grade only classes.
Bug Fix - Extra delete button removed from messages display, and the ability to delete selected messages works properly. Applies to Simplegradebook Pro schools and users only.
Bug Fix - Messages selected for a student are correctly filtered. Applies to Simplegradebook Pro schools and users only.