chore: remove per file license headers

baRSS/Core Data/Feed+Ext.h

@@ -1,25 +1,3 @@
-//
-//  The MIT License (MIT)
-//  Copyright (c) 2018 Oleg Geier
-//
-//  Permission is hereby granted, free of charge, to any person obtaining a copy of
-//  this software and associated documentation files (the "Software"), to deal in
-//  the Software without restriction, including without limitation the rights to
-//  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
-//  of the Software, and to permit persons to whom the Software is furnished to do
-//  so, subject to the following conditions:
-//
-//  The above copyright notice and this permission notice shall be included in all
-//  copies or substantial portions of the Software.
-//
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-//  SOFTWARE.
-
 @import Cocoa;
 #import "Feed+CoreDataClass.h"
 @class RSParsedFeed;