Destroying calendar after plugin quits.
* Changed place where CalendarPlugin instance is first created.
* Added comments to calendarView functions.
Commented functions on util.py
Commented functions on background.py
Commented functions on header.py
Commented functions on drawtask.py
* Removed some unnecessary variables on DrawTask.
Commented functions on link_label.py
Finished commenting functions on view.py
Finished commenting functions on month_view.py
* Removed duplicate function in MonthView (View already had it).
Commented functions on all_day_tasks.py
Finished commenting on week.py
Removed unused file taskview.py.
* TaskEditor started being used after integration with GTG.
Commented functions on controller.py
Commented functions on grid.py