Merge pull request #1 from mphoward/master

update personal forked branch
Merge pull request #2 from mphoward/master

merge trajectory updates
PDB Trajectory conversion

Frames -> Trajectory
Bug fix and compilation check for PDBTrajectory
GRO Trajectory Conversion

Frames -> Trajectory for GRO format
GROTrajectory Box Read Fix
XTC & TRR Trajectory

- external library added (xdrfile)
- Makefile modified
Re-ordered xdrfile library location

Also made changes to Makefile to minimal
Merge pull request #2 from skim459/master

Merge PDB, GRO, XTC, and TRR readers