Expose the SGCT statistics information through a property in the RenderEngine (closes #2195)

include/openspace/engine/windowdelegate.h

@@ -105,6 +105,8 @@ struct WindowDelegate {
     uint64_t (*swapGroupFrameNumber)() = []() { return uint64_t(0); };
 
     void (*setScreenshotFolder)(std::string) = [](std::string) {};
+
+    void (*showStatistics)(bool) = [](bool) {};
 };
 
 } // namespace openspace

include/openspace/rendering/renderengine.h

@@ -180,6 +180,7 @@ private:
 
     properties::IntListProperty _screenshotWindowIds;
     properties::BoolProperty _applyWarping;
+    properties::BoolProperty _showStatistics;
     properties::BoolProperty _screenshotUseDate;
     properties::BoolProperty _showFrameInformation;
     properties::BoolProperty _disableMasterRendering;