planner: pass in_planner down to TemplateLayout

The TemplateLayout prints different dives depending on
whether the planner is active. Instead of accessing a
global variable, pass the status down from the MainWindow.
That's all quite convoluted, since there are multiple
layers involved.

On the positive side, the in_planner() function has now
no users an can be removed.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/qthelper.h

@@ -137,7 +137,6 @@ extern "C" {
 #endif
 
 char *printGPSCoordsC(const location_t *loc);
-bool in_planner();
 bool getProxyString(char **buffer);
 bool canReachCloudServer();
 void updateWindowTitle();