// output of ./demo/bits/hilbert-moves-demo.cc:
// Description:
//% Moves and turns of the Hilbert curve.

arg 1: 6 == ldn  [number of moves == 2**ldn]  default=6
 dx+dy: ++-+++-+++----++++-+++-+++----++++-+++-+++----+---+---+---++++-
 dx-dy: +----+++-+++-+++-++++---+---+----++++---+---+----++++---+---+--
   dir: >^<^^>v>^>vv<v>>^>v>>^<^>^<<v<^^^>v>>^<^>^<<v<^<<v>vv<^<v<^^>^<
  turn: 0--+0++--++0+--0-++-0--++--0-++00++-0--++--0-++-0--+0++--++0+--
