INT 15 - DESQview v2.00+ - "PUSHKEY" - PUT KEY INTO KEYBOARD INPUT STREAM
        AX = DE10h
        BH = scan code
        BL = character
Return: nothing
Notes:  a later read will get the keystroke as if it had been typed by the user
        multiple pushes are read last-in first-out
        if a script exists for the pushed key in the current application, the
          script will be executed
        early copies of DV 2.00 destroy AX, BX, ES, and DI