[enhancement] [WBT + WbW] Set upper and lower limit for contours

[CarlosGrohmann]

I guess this applies to both WBT and WbW. When creating contours (from a raster or vector), we have the option to set the base contour level, but we can't set a 'top' limit. Having this option would allow us to create contours for a slice of a DEM, for instance (such as creating two/more sets of contours, with different spacing based on the slope when working on areas with both mountains and plains)

[jblindsay]

This is a good idea Carlos. I can certainly add this feature.