Add auto perspective correction to GUI

Add three buttons for correcting pitch, yaw, or both. Horizontal and/or
vertical tilt adjusters are updated with the automatically computed
values.

rtgui/toolpanelcoord.h

@@ -301,6 +301,7 @@ public:
     // rotatelistener interface
     void straightenRequested () override;
     void autoCropRequested () override;
+    void autoPerspRequested (bool corr_pitch, bool corr_yaw, double& rot, double& pitch, double& yaw) override;
     double autoDistorRequested () override;
 
     // spotwblistener interface