Issue #287 : Shortcuts now rely on Shortcut instances. Shortcut key can be changed dynamically.

src/js/tools/drawing/SimplePen.js

@@ -9,7 +9,7 @@
   ns.SimplePen = function() {
     this.toolId = 'tool-pen';
     this.helpText = 'Pen tool';
-    this.shortcut = 'P';
+    this.shortcut = pskl.service.keyboard.Shortcuts.TOOL.PEN;
 
     this.previousCol = null;
     this.previousRow = null;