*   *Breaking*: `hlMags` field in `HHT v n a` now contains `n + 1` items,
    instead of `n` items.  Use `V.init` to regain the original behavior.
*   Added `hlInitPhase` field to `HHTLine`, to denote the initial phase that an
    HHT Line starts at.
*   Added `hhtResidual` field to `HHT`, to store the residual of the original
    EMD.
*   Add `ihht` and `ihhtEmd`, to invert Hilbert-Huang Transform and reconstruct
    the original series (or the original EMD).
*   Begin benchmarking `hht` and `ihht`.