Preserve initial conditions on spin vectors, so that spin rotors can be trivial
Change name of S_S to S_chi for consistency
Undo accidental deletion of variable name
A couple more variable-name changes for consistency
Explicitly set the non-evolution of tiny spins
Decrease level at which spin is assumed to be constant
Clarify construction of spinor; closes #22
Merge pull request #23 from moble/ChangeSpinEvolution

Change spin evolution; closes #22