First official release.
Content
-----------
Simple collective variable classes for molecular dynamics simulations using OpenMM:
1. **Distance**: the distance between two atoms
2. **Angle**: the angle formed by three atoms
3. **Torsion**: the torsion angle formed by four atoms
4. **RadiusOfGyration**: the radius of gyration of a group of _n_ atoms
Besides the methods and attributes inherited from its underlying OpenMM Force class, each collective variable class includes the following methods:
1. **getArguments**: inspects the arguments needed for constructing an instance of this collective
variable
2. **setUnit**: sets the unit of measurement of this collective variable
3. **getUnit**: gets the unit of measurement of this collective variable
4. **evaluateInContext**: evaluates this collective variable at a given OpenMM Context
5. **effectiveMassInContext**: computes the effective mass of this collective variable at a given OpenMM Context
Serialization/Deserialization:
A module `serializer` is included, containing the following functions:
1. **serialize**: serializes a collective variable object in YAML format
2. **deserialize**: deserialize a collective variable object from an IO string stream