Get rid of AnyAction

The AnyAction type isn't needed any more; just use Action with no type parameters. This also
resolves reduxjs#2508.

Author: pelotom

index.d.ts

@@ -20,17 +20,6 @@ export interface Action<T = any> {
   type: T;
 }
 
-/**
- * An Action type which accepts any other properties.
- * This is not part of `Action` itself to prevent users who are extending `Action`.
- * @private
- */
-export interface AnyAction extends Action {
-  // Allows any extra properties to be defined in an action.
-  [extraProps: string]: any;
-}
-
-
 /* reducers */
 
 /**