Get rid of absurd config.ignoreKeys. Closes issue #406.

common/modules/config.jsm

@@ -324,12 +324,6 @@ var ConfigBase = Class("ConfigBase", {
      */
     host: null,
 
-    /**
-     * @property {Object} A map between key names for key events which should be ignored,
-     *     and a mask of the modes in which they should be ignored.
-     */
-    ignoreKeys: {}, // NOTE: be aware you can't put useful values in here, as "modes.NORMAL" etc. are not defined at this time
-
     /**
      * @property {[[]]} An array of application specific mode specifications.
      *     The values of each mode are passed to modes.addMode during