Fixed --start vs. --start-rule inconsistency between help and actual option processing code.

Rakefile

@@ -22,7 +22,7 @@ file "lib/pegjs-runtime-#{version}.min.js" => "lib/runtime.js" do |t|
 end
 
 file "lib/metagrammar.js" => "lib/metagrammar.pegjs" do |t|
-  system "bin/pegjs --start grammar PEG.grammarParser lib/metagrammar.pegjs"
+  system "bin/pegjs --start-rule grammar PEG.grammarParser lib/metagrammar.pegjs"
 end
 
 desc "Build the minified parser runtime"

bin/pegjs-main.js

@@ -95,10 +95,10 @@ var args = Array.prototype.slice.call(arguments, 1);
 while (args.length > 0 && isOption(args[0])) {
   switch (args[0]) {
     case "-s":
-    case "--start":
+    case "--start-rule":
       nextArg();
       if (args.length === 0) {
-        abort("Missing parameter of the -s/--start option.");
+        abort("Missing parameter of the -s/--start-rule option.");
       }
       startRule = args[0];
       break;