DenormalizedBrain - think for 2 plies

[lrozenblyum]

While normalized brain is taught to think for 2 plies in #235, the denormalized one lacks this possibilities.
Relates to #290
We should support 2 plies thinking in the denormalized brain.
(?) Maybe blocked by a decision: do we need the denormalized brain?

• Denormalized brain should be affected
  • If Normalized brain is reused, ensure the source is truly in [ 0, 1 ] range
  • Think for depth 1 or 2
  • Provide string representation correctly depending on the depth (name method)