Various cleanup and comment improvement, done as part of code review,…

… see #1.

js/neuron/model/AxonMembraneState.js

@@ -1,6 +1,8 @@
 //  Copyright 2002-2014, University of Colorado Boulder
 
 /**
+ * A type that represents the state of the axon membrane, used primarily for record and playback.
+ *
  * @author John Blanco
  * @author Sharfudeen Ashraf (for Ghent University)
  */
@@ -11,8 +13,7 @@ define( function( require ) {
   var inherit = require( 'PHET_CORE/inherit' );
 
   /**
-   *
-   * @param {TravelingActionPotentialState}travelingActionPotentialState
+   * @param {TravelingActionPotentialState} travelingActionPotentialState
    * @constructor
    */
   function AxonMembraneState( travelingActionPotentialState ) {
@@ -21,13 +22,11 @@ define( function( require ) {
 
   return inherit( Object, AxonMembraneState, {
     /**
-     * Return the state of the traveling action potential.  If null, no
-     * travling action potential exists.
+     * Return the state of the traveling action potential.  If null, no traveling action potential exists.
      * @return
      */
     getTravelingActionPotentialState: function() {
       return this.travelingActionPotentialState;
     }
   } );
-
 } );