Implemented security protocol on the screen base

The changes made here should apply to all screen objects
Implemented security protocol on the contact boundary
Implemented security protocol on the contact screen
Added a checksum for verifying a change to a users security access

This file calculates the checksum and every object that has the a
security protocol implemented copies the checksum value at the time of
access evaluation. When the security access needs to be reevaluated the
checksums are compared to determine if the reevaluation is neccessary