Native print

[scgilardi]

• print1 - an example with native code to print an integer via write to stdout

  • equivalent to the built-in print, but written in porth
  • with the advantage of printing negative integers with a leading minus when compiled just like when simulated

• includes an additional stack word rot because without it, using the 3rd item on the stack is inconvenient

• implemented as an example because perhaps we don't want to expand print inline on every use.

  • maybe porth will support a callable procedure abstraction at some point

• includes signmag that converts an integer to sign-magnitude form

  • possibly useful for std.porth at some point