1. Add a flag to disable this->ResetCache()
2. Remove an unnecessary condition when advancing this->CurrentTimeStep.
   This condition causes extra time requests in a coprocessing work flow
3. More graceful handling of the situation when there is only one time step
4. Fixes a few warnings and stylistic issues.

Change-Id: Id562c302a5e5503296a8787dc329607a9389eb18