Added field renaming capability.
Added field renaming capability.

E.g., use this to select a primary key field by renaming the field to "_id".

Kitware/tangelo,mathstuf/tangelo,mathstuf/tangelo,Kitware/tangelo,ecohealthalliance/tangelo,ecohealthalliance/tangelo,ecohealthalliance/tangelo,Kitware/tangelo,aashish24/tangelo,mathstuf/tangelo,aashish24/tangelo,aashish24/tangelo