Fix FilterCheckpoint
This fixes a bug with parsing the OutputFrequency
parameter of FilterCheckpoint.
I also made checkpoint 0 correspond to the initial condition, so that it is consistent with the behaviour from IO_CheckSteps.
This fixes a bug with parsing the OutputFrequency
parameter of FilterCheckpoint.
I also made checkpoint 0 correspond to the initial condition, so that it is consistent with the behaviour from IO_CheckSteps.