Add isSdUsed() query for third party

src/esp3dlib.cpp

@@ -31,6 +31,9 @@
 #include "core/esp3doutput.h"
 #include "core/commands.h"
 #include <soc/rtc_wdt.h>
+#ifdef SDSUPPORT
+#include "modules/filesystem/esp_sd.h"
+#endif //SDSUPPORT
 
 
 Esp3DLib esp3dlib;
@@ -75,6 +78,16 @@ bool Esp3DLib::parse(char * cmd)
     return false;
 }
 
+bool Esp3DLib::isSdUsed()
+{
+#ifdef SDSUPPORT
+    return ESP_SD::isEnabled();
+#else
+    return false;
+#endif //SDSUPPORT
+
+}
+
 //Idletask when setup is done
 void Esp3DLib::idletask()
 {