Disabled Clear Tree Filter button when no tree filter is applied
Added double clicking and right clicking features in sub requirement tree
Started adding images to user manual
Merge branch 'dev-set3-iteration5' of github.com:333fred/wpi-suite-tng into dev-set3-iteration5
Pop-up menus for sub requirement tree is working. Can remove parent or select a child to remove
Merge branch 'dev-set3-iteration5' of github.com:333fred/wpi-suite-tng into dev-set3-filter