fix arduino.h name to keep compatibility on Linux

Pavlos Ratis · Pavlos Ratis · commit cc80553f52d2 · 2016-01-08T13:45:32.000+02:00
Linux is case sensitive and the sketches
that use sx1509_registers.h fail to compile
so I switched the arduino.h include to capitalcase.
diff --git a/src/sx1509_registers.h b/src/sx1509_registers.h
@@ -1,6 +1,6 @@
 #ifndef SX1509_REGS_H
 #define SX1509_REGS_H
-#include "arduino.h"
+#include "Arduino.h"
 
 /* 
 	sx1509_registers.h
