The shell command simulator in LPC.

These lfuns are used in the interaction of the command objects.

status help(string arg);
	Called in the master object to get help. If there is help on 
	this subject written out, this should return 1 else 0;

object command_object(string * arg);
	Called in the master object with the argument vector. It returns 
	a newly created or old reusable command object. The choise is left 
	to the master.

status start(string * arg, object previous_object);
	Called in the object returned by command_object, to initiate the
	program. This is the only way to determin what object I shall call
	to get my input from. If previous_object is 0 then there is no input.
	When this is called all commands are initializes so I could choose to
	read all input now if I want to.
	This does command line parsing. If this goes wrong it sets notify_fail
	and returns 0.

string output();
	Called in the previous object to get output from that command (i.e. 
	input to myself). The output is returned. This could be a string of
	any length. Zero length is possible! Several lines is also possible.
	When we don't have any more output to give return 0; meaning end of 
	file.

status exit_status();
	Called in the previous object if we want to know the exit_status.
	Usually 0 or not existant meaning, all went well.

void done();
	Signals that the process is done, the object can selfdestruct.