Removed any reference to end_day since it wasn't being used
* No more reference to self.view_end_day
* Now the date_generator function uses only @start and @numdays as parameter.
* Removed self.footer
Improved drag and drop, included support to enlarge/shrink tasks.
* Now the task being dragged itself is changed, instead of a copy.
Change the cursor when moving/hovering a task.
Fixed bug when task was deleted
* Removed reference to location where the task was drawn before