Specify options for image generating tool

[gonuke]

1. Slice[=args]

   • with no args - default direction and location
   • with args : [(<x,y,z>,val),(<x,y,z>,val),....] produces one image for each tuple with slice at plane <x,y,z>=val

2. Clip[=args]

   • with no args - default octant, rotation and midpoint
   • with args : [{loc:(x,y,z),octant:(+/-1,+/-1,+/-1),rot:(alpha,beta,gamma)},...] produces one image for each dictionary
   • if only partially defined - default rotation depends on octant
   • default position is center of data (not origin and not center of geometry)

3. Threshold=expr

   • expr = tagname > val | tagname < val | tagname = (min,max)

4. Pseudo = tagname [, log|lin, lower, upper]

5. Contour = tagname

[leschultz]

I have added the options desired.