added .moo (parser definitions) to Mercury extension list

samples/Moocode/toy.moo

@@ -0,0 +1,19 @@
+@verb toy:do_the_work this none this
+@program toy:do_the_work
+if (this.wound)
+  if ($object_utils:isa(this.location,$room))
+    this.location:announce_all(this.name," ", this:continue_msg());
+    this.wound = this.wound - 1;
+    if (this.wound)
+      fork (15)
+        this:do_the_work();
+      endfork
+    else
+      this.location:announce_all(this.name, " ", this:wind_down_msg());
+    endif
+  endif
+  if (this.wound < 0)
+    this.wound = 0;
+  endif
+endif
+.