Support toggling captcha with space bar.

src/Posting/Captcha.v2.coffee

@@ -26,6 +26,11 @@ Captcha.v2 =
     $.after QR.nodes.com.parentNode, root
 
     $.on counter, 'click', @toggle.bind @
+    $.on counter, 'keydown', (e) =>
+      return unless Keybinds.keyCode(e) is 'Space'
+      @toggle()
+      e.preventDefault()
+      e.stopPropagation()
     $.on window, 'captcha:success', =>
       # XXX Greasemonkey 1.x workaround to gain access to GM_* functions.
       $.queueTask => @save false