Added ability to change time format string for when you're in System

Clock mode. Fixed code so that editing settings in the settings dialog
will now immediately take effect in the program.

canframemodel.h

@@ -36,6 +36,7 @@ public:
     void setFilterState(unsigned int ID, bool state);
     void setAllFilters(bool state);
     void setSecondsMode(bool);
+    void setTimeFormat(QString);
     void loadFilterFile(QString filename);
     void saveFilterFile(QString filename);
     void normalizeTiming();
@@ -62,6 +63,7 @@ private:
     QMutex mutex;
     bool interpretFrames; //should we use the dbcHandler?
     bool overwriteDups; //should we display all frames or only the newest for each ID?
+    QString timeFormat;
     bool useHexMode;
     bool timeSeconds;
     bool useSystemTime;