(Binary Analysis) Updated test answers for new symbolic simplifications
(Binary Simulator) new commands; better mixed interpretation memory state

* Added the "register NAME" command, which is similar to the "registers"
  command but shows only the named register.

* Prune the memory cell list when possible in order to keep it smaller.
  The list is pruned when a read/write address must_equal a memory cell
  that's already stored.

* Memory defaults are generated like for API2: reading a multi-byte
  value from memory initializes the new 1-byte cells with related
  values. E.g., when reading a 4-byte value, the old method might
  have initialized memory to:

      cell a0+0 = v1[8]
      cell a0+1 = v2[8]
      cell a0+2 = v3[8]
      cell a0+3 = v4[8]

  The new method uses:

      cell a0+0 = (extract 0 8 v1[32])
      cell a0+1 = (extract 8 16 v1[32])
      cell a0+2 = (extract 16 24 v1[32])
      cell a0+3 = (extract 24 32 v1[32])

  The benefit of the new method is that if we later read the four-byte
  value at a0 we get back:

      (concat (extract 0 8 v1) (extract 8 16 v1) (extract 16 24 v1)
         (extract 24 32 v1))

   which is automatically simplified back to just "v1[32]".