ProcessRexxCommands

 FUNCTION
 Handle incomming ARexx commands (DICE)

 SYNTAX
 #include <lib/rexx.h>
 ProcessRexxCommands(port)
 struct MsgPort *port;

 DESCRIPTION
 In order to process incomming ARexx commands you must call
 ProcessRexxCommands when you receive the signal RexxSigBit (signal
 mask is (1 << RexxSigBit)).

 Passing NULL to this routine will cause DICE to scan ALL KNOWN ARexx
 ports belonging to this program... that is, the master port and all
 created ports.  DICE will call DoRexxCommand for each ARexx command
 received as well as weed out returned messages from any ARexx
 commands we have sent that are still in progress.

 If you wish, you can pass a specific message port to have DICE only
 process ARexx commands received on a specific port, but beware that
 your Wait on the signal bit has cleared the signal and you should be
 sure to process all message ports before calling Wait again, else
 risk leaving unprocessed ARexx messages queued in and then blocking
 in Wait.

 INPUTS
 struct MsgPort *port;

 Message port to process or NULL to process all ports.