Add a proper build system

Also lowers the minimum required Qt version to 5.5.

src/QtWidgets/QtApplication.h

@@ -0,0 +1,59 @@
+/*
+ * 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 "QtGUIApplication.h"
+
+#include <QApplication>
+
+@interface QtApplication: QtGUIApplication
+@property (readonly) QApplication *qApplication;
+@property bool autoSIPEnabled;
+@property int cursorFlashTime;
+@property int doubleClickInterval;
+@property of_dimension_t globalStrut;
+@property int keyboardInputInterval;
+@property int startDragDistance;
+@property int startDragTime;
+@property (copy) OFString *styleSheet;
+@property int wheelScrollLines;
+
+- initWithQApplication: (QApplication*)qApplication;
+- (void)aboutQt;
+- (void)closeAllWindows;
+@end
+
+namespace ObjQt {
+
+static OF_INLINE QtApplication*
+toOF(QApplication *qApplication)
+{
+	return [[[QtApplication alloc]
+	    initWithQApplication: qApplication] autorelease];
+}
+
+static OF_INLINE QApplication*
+toQt(QtApplication *application)
+{
+	return [application qApplication];
+}
+
+}