setPartialTitrationStates now supports multiple simultaneous titration state changes.
update_ncmc still has original random switching between 1 and 2 draws.  This
will ultimately need to accomodate charge neutral perturbations, biased selection
probabilities, etc, but setPartialTitrationStates should remain mostly unchanged.
setTitrationStates (the original function) does not yet support lists of titrations.

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