Add support for CGA "context functions" #119
Description
verify support (and complete) for CGA "context functions" listed here:
https://doc.arcgis.com/en/cityengine/latest/cga/cityengine-cga-introduction.htm#ESRI_SECTION1_AEF99BBB7D64448CBA821BE737C842F2
- contextCompare
- contextCount
- minimumDistance