Make About window scrollable
Make About window scrollable

On some OSes/configurations/screens, the list of credits in the About window doesn't fit until the window is resized. Adding a scrollview helps in these cases.

Curahelper/Cura,hmflash/Cura,hmflash/Cura,ynotstartups/Wanhao,ynotstartups/Wanhao,Curahelper/Cura,fieldOfView/Cura,fieldOfView/Cura