Add task edit stage
GUI's limited in it's width, so displaying description or deadline time in Task tab's table view is generally a bad idea. Application should provide a way to edit tasks like activities (through modal stage). Task edit stage should contain:
- Name text field
- Tags chip view
- Description text field
- Deadline timestamp text field
- Done timestamp text field
So now we also should be able to change timestamp which describes task finish time, while still keeping the easy way of checking the checkbox. Table view should remove Deadline and Description columns, but instead add Status column which should contain difference between deadline timestamp and current timestamp. If difference is positive, it should say "x u remaining", where u - optimal time unit, x - value. Text should be green or smth like that. If difference is negative, it should tell "Overdue for x u" and text should be red.