Rework the condition capture user experience:
- User must now take a screenshot of the full screen.
- Then the user can move the selector on this screenshot to select the correct area.
- Screenshot can be moved/zoom to easily define small conditions.
Those changes have been made based on the enhancements #9 and #15
Fixes:
- screenshots will now be faster on low refresh time screens.
- permission dialog is now scrollable (fixes #31, thanks to @yuhuitech)