Task-indicator

- Added a popup menu to start/stop tasks in the search dialog.

- Calling bugwarrior from menu no longer blocks the UI.

- Active tasks are shown with bold font in the search dialog.

- Long notes now have a vertical scroll-bar and don't extend
the window vertically.

- Use real task urgency, which tasks are now sorted by.

- Fixed a bug with tasks that have no project assigned.
- Strip trailing URLs from task descriptions.
- Moved project name to the end of the menu item, and only show
it if the task has one.
- Don't open task webpage on start (there's a separate button for that).
- Fixed an error when a task had no priority.
- Database location is now requested from TaskWarrior, not hard-coded.