Replaced Functionality by Activity.pm

Bye Bye Birdie
Added day and term classes to help convert day/term strings to numbers

Will eventually be deleted when SimpleTimeslot is no longer needed and and
I'm comfortable using actual datetime objects for start/duration
Interface package for use by each and every kind of constraint.

Should consider adding SAT/Graph colouring functions to these? How??
Output a series of newline and an asterisk trail
to visually help in finding the start of test outputs
SimpleTimeslot now deals with Days and Terms
Intersection code from timeslot had to be deleted, it was bloatware
Deleted more bloatware. No obvious difference between student and staff.

Both can be and currently are represented by Person class. A better
question is whether student/staff is a role only depending on Activity
situation?
Removed a bit of duplication
ActivityHolder (Nick Schedule) and tests improved

References for persons, modules and rooms, now point to it
Changed Schedule to cope with changes made to SimpleTimeslot
Added to_string functions to ease with debugging
Comparison and check clash function for Activity
Only timeslots are checked for comparison and clashes. Other constraints
are handled by constraint objects
Added support for ActivityHolders (as an object)
Sort unit test for activity.

Activities are now sorted by timeslot comparisons
Clash test for Person, must not be in two places at once
Person clash
Incomplete classes for LunchBreak Constraints and Grabbing Modules