Add a proper build system

Also lowers the minimum required Qt version to 5.5.

QtGui/QtPaintDevice.h

@@ -1,57 +0,0 @@
-/*
- * Copyright (c) 2017, Jonathan Schleifer <js@heap.zone>
- *
- * https://heap.zone/git/objqt.git
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice is present in all copies.
- *
- * 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.
- */
-
-#import <ObjFW/ObjFW.h>
-
-#include <QPaintDevice>
-
-@protocol QtPaintDevice
-- (QPaintDevice*)qPaintDevice;
-- (int)colorCount;
-- (int)depth;
-- (int)devicePixelRatio;
-- (double)devicePixelRatioF;
-- (int)height;
-- (int)heightMM;
-- (int)logicalDPIX;
-- (int)logicalDPIY;
-- (QPaintEngine*)paintEngine;
-- (bool)paintingActive;
-- (int)physicalDPIX;
-- (int)physicalDPIY;
-- (int)width;
-- (int)widthMM;
-@end
-
-@interface QtPaintDevice: OFObject <QtPaintDevice>
-@property (readonly) QObject *qObject;
-@end
-
-namespace ObjQt {
-
-static OF_INLINE QPaintDevice*
-toQt(QtPaintDevice *paintDevice)
-{
-	return [paintDevice qPaintDevice];
-}
-
-}