Dialog RoiStats4D:  added the Info button so the Information could be displayed more conveniently for the user.

Dialog RoiStats4D:   Implemented an intelligent background color management.

Dialog RoiStats4D:  User is now able to use   {LEFT,RIGHT} keyboard keys to scroll in time when this dialog is open.  The 4D volume and the Curves in the dialog box are updated correspondingly.

Among many uses this function allows to reuse this dialog in the BAT (Bolus Arrival Time)  verification procedure.

Fixed several issues related to 4D ROIs and the corresponding layer control dialog box:
a) 4D ROI default name RAW extension
b) 4D ROI default RAW save format
c) In RoiStat4D dialog box, the timepoints not containing the actual ROI are drawn as "white" nodes on the curve.