Move qt-ui to desktop-widgets

Since we have now destkop and mobile versions, 'qt-ui' was a very
poor name choice for a folder that contains only destkop-enabled
widgets.

Also, move the graphicsview-common.h/cpp to subsurface-core because
it doesn't depend on qgraphicsview, it merely implements all the
colors that we use throughout Subsurface, and we will use colors on both
desktop and mobile versions

Same thing applies for metrics.h/cpp

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

desktop-widgets/about.h

@@ -0,0 +1,21 @@
+#ifndef ABOUT_H
+#define ABOUT_H
+
+#include <QDialog>
+#include "ui_about.h"
+
+class SubsurfaceAbout : public QDialog {
+	Q_OBJECT
+
+public:
+	explicit SubsurfaceAbout(QWidget *parent = 0, Qt::WindowFlags f = 0);
+private
+slots:
+	void on_licenseButton_clicked();
+	void on_websiteButton_clicked();
+
+private:
+	Ui::SubsurfaceAbout ui;
+};
+
+#endif // ABOUT_H