Merge branch 'master' of github.com:lmccart/p5.js

Author: Lauren McCarthy

src/core/core.js

@@ -166,7 +166,8 @@ define(function (require) {
       'touchstart': null,
       'touchmove': null,
       'touchend': null,
-      'resize': null
+      'resize': null,
+      'blur': null
     };
     this._loadingScreenId = 'p5_loading';
 

src/input/keyboard.js

@@ -223,6 +223,15 @@ define(function (require) {
       }
     }
   };
+  /**
+   * The onblur function is called when the user is no longer focused
+   * on the p5 element. Because the keyup events will no fire if the user is
+   * not focused on the element we must assume all keys currently down have 
+   * been released.
+   */
+  p5.prototype.onblur = function (e) {
+    downKeys = {};
+  };
 
   /**
    * The keyIsDown function checks if the key is currently down, i.e. pressed.