First draft of the trajectory_example code.
Roughly working version of trajectory_example.

Now the point is to clean this up until it works smoothly.
Solvect/Solvent.... I've heard it both ways.
Reports Ramachandran angles.
trajectory_example now contains state/iface defs.

Also switched to amber96 to be consistent with JDC and PGB's earlier papers
on Ala-dipeptide.
LambdaVolumePeriodic and working tests.
Correction to atoms labelled as psi atoms.

Doesn't change any behavior, just fixes typos. Turns out PDB counts from 1,
we count from 0.
Progress on the example; mainly commit-as-stash.
Initial work toward Exit/EnterXEnsembles.

Also, corrects a few points on volume, and adds skeletons of the test
classes for these ensembles.
Steps toward implementing ensemble tests.
Tests for Enters/ExitsXEnsemble.

Pretty setup, with a few clever hacks to make tests more manageable.
Exits/EntersXEnsemble. Code passes tests.
Merge branch 'enter_exit_ensembles' into example_traj

So I can use my EntersXEnsemble and ExitsXEnsemble classes on the example
script I'm assembling.
Commit-as-stash to make SequentialEnsembles.
Intial work on SequentialEnsemble, incl tests
Draft for SequentialEnsemble.__call__.

Also includes InXEnsembles.__str__()
Further work on tests, esp. for SequentialEnsemble.
Added tests for minus_ensemble append/prepend.
Slow progress. This algorithm is difficult.
SequentialEnsemble.can_append passes tests.

Holy crap that was hard. Fortunately, with this as the template, the rest
should be easier.