GUI: Improve DoubleSpinBox
- [x] Support scientific notation on input
- [x] Display number in scientific notation where appropriate (#858)
- [x] Don't display trailing zeros (#861)
- [x] Increase step upon repeated action; reduce step upon change of direction
- [x] Correct display of negative numbers ~~(broken in j.870a)~~
- [x] Respect limits given through DoubleProperty
issue