Changes in version 0.0.0.9000                      

  - Initial development version.
  - progression_ratios() computes grade progression ratios from
    historical grade-level enrollment, with configurable averaging
    (mean, geometric, median, last, weighted).
  - projection_matrix() assembles the projection matrix from progression
    ratios.
  - project_enrollment() projects enrollment forward an arbitrary
    horizon, taking the entry grade exogenously.
  - project_enrollment() accepts a prebuilt per-year schedule of
    projection steps as an alternative to the ratios/horizon/entry
    arguments.
  - swing_schedule() builds a swing/recovery projection schedule for a
    school passing through a temporary relocation.