#2881 Color parameters in scripts

[Jeremy Faden]

The code https://github.com/autoplot/dev/blob/master/demos/2019/20190726/paramTypes2019.jy implies that Color parameters are supported, but I get runtime errors with this when I try non-default values.

Also the editor GUI provided for the "color1" parameter is correct, providing a Color Picker GUI, but the icon is a calendar.

[Jeremy Faden]

I tried datum parmaters and they work nicely. The code for both Datum and Color should be similar.