Add Recurrence framework
Implement recurrence subclasses
Added drop down and date picker for recurrence

in NewTaskPanel
Support for Recurrence adding in new task panel

Recurrence class changes are in different commit to allow for future backing out
Changes to recurrence task to allow for not always adding tasks
Allow recurrence based upon start date or due date

Also fix size of panel, modify alerts to indicate start or due date required instead of just due date.
NewTaskPanel will now properly set the date to 11:59
Merge remote-tracking branch 'origin/3.7_Recurrence'

Signed-off-by: Eric Kinnear <eric.kinnear@gmail.com>

Conflicts:
	src/user_interface/NewTaskPanel.java

Resolved all conflicts, merged with master.