Basic measuring scoop (any size) with OpenSCAD source, Customizer version

The same as the original (https://www.thingiverse.com/thing:4208515) but works with the OpenSCAD customizer.

Other changes:
- remove the built-in table of parameter and replaces it with the customizer.
- adds the ability to move the handle up to the top or down to the bottom, or anywhere in between. When at the top, you can print this upside down and add support only for the scoop cup.
- better error checking and robustness for handle size.

I'm not sure this works with the ancient Thingiverse customizer but it works well with the OpenSCAD customizer.