Resolve WB-777 Performance problems limited to scrolling volume slices: In the...

Resolve WB-777 Performance problems limited to scrolling volume slices: In the toolbar, there are spin boxes for slice indices and coordinates.  When the user changes a slice index, the corresponding coordinate must be updated and vice verse.  There is a bug with spin boxes in Qt (QTBUG-14529) that results in the spin box issuing two value changed signals when the slot takes 'long' time to execute.  There is also a problem with that if one updates the range (min/max) of a spin box, a signal is emitted even though the spin box has its signals blocked.  The combination of these problems resulted in a backup of key events when the user holds down an arrow key in a spin box, and, after the user releases the key, many key events are received and the slice continue to scroll for a few seconds.  When updating the spin boxes, the ranges (minimum and maximum) values are updated only if they are different than the current range of the spin box.  This has eliminated the signal caused by avoiding update of the spin boxes range and prevents the volumes slices from scrolling when the arrow key is released.  This problem with the slices continuing to scroll was only seen on Linux and not on Mac even though Mac still had the problem with the signals (windows unknown).