Fix ConformerParser to use const std::string &
Fix ConformerParser to use const std::string &

In #627, `readAmberTrajectory` in ConformerParser.h is updated to use `const std::string &`. This updates the corresponding method in ConformerParser.cpp to match. I needed to do this to compile RDKit with contrib.
bp-kelley/rdkit,rvianello/rdkit,rvianello/rdkit,ptosco/rdkit,jandom/rdkit,greglandrum/rdkit,jandom/rdkit,greglandrum/rdkit,rdkit/rdkit,greglandrum/rdkit,jandom/rdkit,bp-kelley/rdkit,bp-kelley/rdkit,ptosco/rdkit,rvianello/rdkit,adalke/rdkit,adalke/rdkit,adalke/rdkit,adalke/rdkit,adalke/rdkit,greglandrum/rdkit,rvianello/rdkit,greglandrum/rdkit,greglandrum/rdkit,rdkit/rdkit,jandom/rdkit,ptosco/rdkit,rvianello/rdkit,jandom/rdkit,rvianello/rdkit,rdkit/rdkit,rvianello/rdkit,bp-kelley/rdkit,ptosco/rdkit,adalke/rdkit,jandom/rdkit,adalke/rdkit,jandom/rdkit,bp-kelley/rdkit,adalke/rdkit,bp-kelley/rdkit,bp-kelley/rdkit,jandom/rdkit,ptosco/rdkit,rdkit/rdkit,greglandrum/rdkit,rdkit/rdkit,bp-kelley/rdkit,rvianello/rdkit,rdkit/rdkit,rdkit/rdkit,ptosco/rdkit,rdkit/rdkit,greglandrum/rdkit,ptosco/rdkit,ptosco/rdkit