Add central config.pri to handle default values for some build options

config.pri

@@ -0,0 +1,37 @@
+#functions to automatically initialize some of YACReader's build options to
+#default values if they're not set on build time
+#for a more detailed description, see INSTALL.TXT
+
+#check Qt version
+QT_VERSION = $$[QT_VERSION]
+QT_VERSION = $$split(QT_VERSION, ".")
+QT_VER_MAJ = $$member(QT_VERSION, 0)
+QT_VER_MIN = $$member(QT_VERSION, 1)
+
+lessThan(QT_VER_MAJ, 5) {
+error(YACReader requires Qt 5 or newer but Qt $$[QT_VERSION] was detected.)
+	}
+lessThan(QT_VER_MIN, 5):!CONFIG(no_opengl)	{
+	CONFIG += legacy_gl_widget
+	message ("Qt < 5.4 detected. Using QGLWidget for coverflow.")
+	}
+	
+#build without opengl widget support
+CONFIG(no_opengl) {
+	DEFINES += NO_OPENGL
+}
+
+!CONFIG(unarr):!CONFIG(7zip) {
+	unix {
+		!macx {
+				CONFIG+=unarr
+			}
+		else {
+				CONFIG+=7zip
+			}
+	
+		}
+	win32 {
+			CONFIG+=7zip
+		  }
+}