Fix c++11 compilation (need full declaration for std::map construction)
Finish fixing off by one error in out-of-bound check.

Avoid reading pass the end of an array in TTreeFormula.
This fixes http://root.cern.ch/phpBB3/viewtopic.php?t=16969.

This finishes 193602b2ad43ac3ca6786ea53f52c453e3e55f90.