GitLab

* Created CustomVolumeForce

* Serialization for CustomVolumeForce

* Documentation for CustomVolumeForce

* Code simplification

* Removed unused code

* Can use getPlatform() instead of getPlatformByName()

* More concise arguments for getState()

Converted the routine for identifying molecules from a recursion to a loop.  This avoids stack overflows with very long linear molecules.

Modified the API for lots of classes so that the number of particles/bonds/etc. need not be specified in the constructor.

Continuing to implement ReferencePlatform (implemented kinetic energy calculation and LangevinIntegrator)

Created a test case for StandardMMForceFieldImpl's findExclusions() method.  Fixed some bugs that it found.  Created a CMake script and configured it for building and running test cases.