FEATURE #1373: add history of content

This commit contains only core funcionality of displaying history. Module settings must be implemented in each module.

app/Http/routes.php

@@ -81,6 +81,14 @@ Route::group([
     Route::get('users/overview/{state?}/{perPage?}', 'UsersOverview@getOverview')
          ->name('users.overview');
 
+    // history of changes for specified page
+    Route::get('history/{id}', 'History@getOverview')
+         ->name('content.history');
+
+    // history of changes for specified page
+    Route::get('history/{revision}/{id}', 'History@getDiff')
+         ->name('history.diff');
+
     // custom fields
     // ------------------------------