vm/stack library

Classes

Duplicate: Duplicate the top value on the stack and add it
Pop: Command to pop a value off the stack and return it
Push: Push a value onto the stack If a value is not recognised as a command, it is pushed, but we need this wrapper to explicitly push a value
Rotate: Rotate the stack at a given depth
Stack: just fetch the whole stack - mostly a debug method
StackListener: the stack is maintained at the lowest level of FlightVM, with all values pushed, except specific commands which pop