getUnflattenedPosition
Translates a flat list position (the raw position of an item (child or group) in the list) to either a) group pos if the specified flat list position corresponds to a group, or b) child pos if it corresponds to a child. Performs a binary search on the expanded groups list to find the flat list pos if it is an exp group, otherwise finds where the flat list pos fits in between the exp groups.
Return
the group position or child position of the specified flat list position encompassed in a ExpandableListPosition object that contains additional useful info for insertion, etc.
Parameters
flPos
the flat list position to be translated