Add keyboard shortcuts for applying hints

Each is a two-key combo.  Hit Ctrl+H, then Ctrl+C/D/I/R as desired.
Hitting Ctrl+H followed by any other key results in an error beep.

SourceGen/Properties/Resources.Designer.cs

@@ -897,6 +897,15 @@ namespace SourceGen.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Ctrl+H was pressed, waiting for second key of chord....
+        /// </summary>
+        internal static string STATUS_CTRL_H_HIT {
+            get {
+                return ResourceManager.GetString("STATUS_CTRL_H_HIT", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Ready.
         /// </summary>