GH-1876 replace ColumnResizer with a newer, BSD-3 licensed version

Also, keep licensing info only in one file.
The COPYING.md is now a resource and rendered to HTML in the About dialog.

COPYING.md

@@ -201,5 +201,36 @@
 
 # ColumnResizer
 
-	Copyright 2011 Aurélien Gâteau <agateau@kde.org>
-	License: LGPL v2.1 or later (see COPYING)
+	Copyright (c) 2011-2016 Aurélien Gâteau and contributors.
+
+	All rights reserved.
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted (subject to the limitations in the
+	disclaimer below) provided that the following conditions are met:
+
+	* Redistributions of source code must retain the above copyright
+	notice, this list of conditions and the following disclaimer.
+
+	* Redistributions in binary form must reproduce the above copyright
+	notice, this list of conditions and the following disclaimer in the
+	documentation and/or other materials provided with the
+	distribution.
+
+	* The name of the contributors may not be used to endorse or
+	promote products derived from this software without specific prior
+	written permission.
+
+	NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE
+	GRANTED BY THIS LICENSE.  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
+	HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
+	WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+	MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+	DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+	LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+	CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+	SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+	BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+	WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+	OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+	IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.