Added cone H-bond criterion
Consolidated functions, periodic=True by default
Removed a function name that was causing a crash
Restored the constants into the function
Robert's suggested changes
Fixed docstring and angle_triplet2
Renamed wernet_nilsson function
actual content
Merge pull request #1 from rmcgibbo/tests-for-484

additions to PR
Merge pull request #483 from leeping/hbond

Added cone H-bond criterion