Prepare for V1.9, moved older entries out to DevHistory.md

Version bump and change log for new release

Don't let QTreeView steal the mouse back and forward buttons

Reduced debug logging

Don't add default-constructed empty years 0 if no activity during cur…

…rent or last year

Updated screenshot

Change log for V1.7

Added release notes for V1.6.1 and moved older change log out to DevH…

…istory.md

Release notes for stable 1.6 release

Version bump for latest fix