Move subsurface-core to core and qt-mobile to mobile-widgets

Having subsurface-core as a directory name really messes with
autocomplete and is obviously redundant. Simmilarly, qt-mobile caused an
autocomplete conflict and also was inconsistent with the desktop-widget
name for the directory containing the "other" UI.

And while cleaning up the resulting change in the path name for include
files, I decided to clean up those even more to make them consistent
overall.

This could have been handled in more commits, but since this requires a
make clean before the build, it seemed more sensible to do it all in one.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/divesitehelpers.h

@@ -0,0 +1,18 @@
+#ifndef DIVESITEHELPERS_H
+#define DIVESITEHELPERS_H
+
+#include "units.h"
+#include <QThread>
+
+class ReverseGeoLookupThread : public QThread {
+Q_OBJECT
+public:
+	static ReverseGeoLookupThread *instance();
+	void lookup(struct dive_site *ds);
+	void run() Q_DECL_OVERRIDE;
+
+private:
+	ReverseGeoLookupThread(QObject *parent = 0);
+};
+
+#endif // DIVESITEHELPERS_H