Delete objects to avoid memory leaks. (#5)

Author: James Foster

src/Adafruit_SPIDevice.h

@@ -65,6 +65,17 @@ class Adafruit_SPIDevice {
                      BitOrder dataOrder = SPI_BITORDER_MSBFIRST,
                      uint8_t dataMode = SPI_MODE0);
 
+  ~Adafruit_SPIDevice() {
+    if (_spi) {
+      delete _spi;
+      _spi = nullptr;
+    }
+    if (_spiSetting) {
+      delete _spiSetting;
+      _spiSetting = nullptr;
+    }
+  }
+
   bool begin(void);
   bool read(uint8_t *buffer, size_t len, uint8_t sendvalue = 0xFF);
   bool write(uint8_t *buffer, size_t len, uint8_t *prefix_buffer = NULL,