upgrade nom to partial impl of MAIN

nom does MAIN now thanks to tadzik++, but not --help

Author: TimToady

features.json

@@ -808,7 +808,7 @@
         "spec"    : [ ]
       }, {
         "item"    : "MAIN",
-        "status"  : "rm+ rn- n-",
+        "status"  : "rm+ rn+- (no help yet) n-",
         "code"    : [ "http://rosettacode.org/wiki/Guess_the_number/With_feedback_(player)#Perl_6",
                       "http://perl6advent.wordpress.com/2010/12/02/day-2-interacting-with-the-command-line-with-main-subs/" ],
         "spec"    : [ "http://perlcabal.org/syn/S06.html#Declaring_a_MAIN_subroutine" ]