Create pins_arduino.h for Node32s(#64)

variants/node32s/pins_arduino.h

+#ifndef Pins_Arduino_h
+#define Pins_Arduino_h
+
+#define EXTERNAL_NUM_INTERRUPTS 16
+#define NUM_DIGITAL_PINS        40
+#define NUM_ANALOG_INPUTS       18
+
+#define analogInputToDigitalPin(p)
+#define digitalPinToInterrupt(p)    (((p)<40)?(p):-1)
+#define digitalPinHasPWM(p)         (p < 34)
+
+static const uint8_t SDA = 21;
+static const uint8_t SCL = 22;
+
+static const uint8_t SS    = 5;
+static const uint8_t MOSI  = 23;
+static const uint8_t MISO  = 19;
+static const uint8_t SCK   = 18;
+
+#endif /* Pins_Arduino_h */