Shift + cursors to move items in large increments

**Is your feature request related to a problem? Please describe.**
- When moving widgets around it would be good to move them more quickly

**Describe the solution you'd like**
- shift + cursors to move items in large increments, eg. 10px
- could combine other modifiers for 5px, 20px, etc

**Describe alternatives you've considered**
- single pixel moves but key repeat means the app cannot keep up

