(js,css) Improve keyboard shortcuts

- Defined some hotkeys in all modules;
- Added generation of cheat sheet.

UI/Scheduler/English.lproj/Localizable.strings

@@ -579,4 +579,25 @@ vtodo_class2 = "(Confidential task)";
 "Toggle item" = "Toggle item";
 
 /* Aria label for scope of search on events or tasks */
-"Search scope" = "Search scope";
+"Search scope" = "Search scope";
+
+/* Hotkey to create an event */
+"hotkey_create_event" = "e";
+
+/* Hotkey to create a task */
+"hotkey_create_task" = "t";
+
+/* Hotkey to go to today */
+"hotkey_today" = "n";
+
+/* Hotkey to switch to day view */
+"hotkey_dayview" = "d";
+
+/* Hotkey to switch to week view */
+"hotkey_weekview" = "w";
+
+/* Hotkey to switch to month view */
+"hotkey_monthview" = "m";
+
+/* Hotkey to switch to multicolumn day view */
+"hotkey_multicolumndayview" = "c";