Gui: add ShortcutManager to unify shortcut handling

Support longest key sequence match with user defined delay (configurable
through 'Customize -> Keyboard -> Key sequence delay').

Support user defined priority to resolve shortcut conflict through
'Customize -> Keyboard')

Add 'All' category in 'Customize -> Keyboard' to list all command and
showing their shortcuts

Unify macro command shortcut setting (BaseApp/Preferences/Shortcut).

src/Gui/Workbench.cpp

@@ -310,6 +310,8 @@ void Workbench::setupCustomToolbars(ToolBarItem* root, const Base::Reference<Par
 
 void Workbench::setupCustomShortcuts() const
 {
+    // Now managed by ShortcutManager
+#if 0
     // Assigns user defined accelerators
     ParameterGrp::handle hGrp = WindowParameter::getDefaultParameter();
     if (hGrp->HasGroup("Shortcut")) {
@@ -328,6 +330,7 @@ void Workbench::setupCustomShortcuts() const
             }
         }
     }
+#endif
 }
 
 void Workbench::setupContextMenu(const char* recipient,MenuItem* item) const