android_secondary_root_path="/storage/extSdCard/addons" ; modify to your path
Then create "addons" folder in the root of yours external memory, leave iGO folder in internal memory and move only "content" folder in external memory in addons folder. Don't move save folder to the external memory.
This two lines enable me to make igo NextGen run on my android marshmallow (igo nextgen in internal memory and maps in my ext sdcard). More, choosing ext sdcard iGO folder as addon (just replacing addons by iGO in the root path), I can share my maps between iGo Primo and iGo NextGen !