stop-lookhead: demo G-code which stops interpreter lookahead

see this forum thread:
http://www.linuxcnc.org/index.php/english/forum/10-advanced-configuration/25994-abort-msg-in-o-sub?start=12#28355

Related:
see 'G103 Lookahead Mode', page 152,

PMAC-NC2 Pro2 Software reference, Delta Tau Systems Inc

http://www.deltatau.com/manuals/pdfs/PMAC-NC%20PRO2.pdf?id=634701792253582640