There's a memory leakage in HVite when phone-marking lattices.

I've observed that GBytes of memory were used while an utterance is
processed. This happens while

- ProcessObservation() is called for each frame.

- at every call new align structures are allocated in
  'alignHeap'. The latter is reset only after all frames are processed.

- but memory usage after 2000 frames were processed is:

nblk=10906, siz=  3200*40 , used= 34789132, alloc=1395696000 : Align Heap[M]

Maybe function UnlinkAlign() should be called to deallocate unused
lattice structures possibly when DetachInst() is called?