Prevent the window from having zero size on load if closed while minimised
[Feature] Selection box is now rendered using dashed lines in 2D views.
[Feature] Decimal part of selection box/selected brush size is now shown only when it's not 0.
[Fix] Only 3 bottom resize highlights of selection box were rendered.
Added a setting for rendering the selection box with dashed lines
2D views can be panned by holding Space nad moving the mouse (this replaces "Space+LMB" behaviour)
Added a setting for requiring a mouse click to pan the 2D views when space is down
Merge branch 'master' of https://github.com/LogicAndTrick/sledge