Fix BlackMisc header includes

* Include only what is used
* Use forward declaration when possible
* Sorted includes

refs #630

src/blackmisc/settingscache.h

@@ -13,8 +13,14 @@
 #define BLACKMISC_SETTINGSCACHE_H
 
 #include "blackmisc/blackmiscexport.h"
+#include "blackmisc/statusmessage.h"
 #include "blackmisc/valuecache.h"
 
+#include <QObject>
+#include <QString>
+#include <QStringList>
+#include <QtDebug>
+
 namespace BlackMisc
 {
     /*!