allow lowercase modifier chars in the {lhs} arg of :map and related commands

content/mappings.js

@@ -216,6 +216,8 @@ vimperator.Mappings = function() //{{{
     {
         for (var i = 0; i < map.names.length; i++)
         {
+            // only store keysyms with uppercase modifier strings
+            map.names[i] = map.names[i].replace(/([casm]-)/g, function($0, $1) { return $1.toUpperCase(); })
             for (var j = 0; j < map.modes.length; j++)
                 removeMap(map.modes[j], map.names[i]);
         }