Added key-access through chars

Devices/Keyboard/CorsairKeyboard.cs

@@ -32,6 +32,12 @@ namespace CUE.NET.Devices.Keyboard
             private set { throw new NotSupportedException(); }
         }
 
+        public CorsairKey this[char key]
+        {
+            get { return this[_CUESDK.CorsairGetLedIdForKeyName(key)]; }
+            private set { throw new NotSupportedException(); }
+        }
+
         public CorsairKey this[PointF location]
         {
             get { return _keys.Values.FirstOrDefault(x => x.KeyRectangle.Contains(location)); }

Devices/Keyboard/Enums/CorsairKeyboardKeyId.cs

@@ -5,6 +5,7 @@ namespace CUE.NET.Devices.Keyboard.Enums
 {
     public enum CorsairKeyboardKeyId
     {
+        Invalid = 0,
         Escape = 1,
         F1 = 2,
         F2 = 3,