spi.hpp: Add C++ wrapper around Spi

* maa_spi_context becomes an opaque pointer
* C++ wrapper class Spi created
* swig now uses C++ wrapper Gpio to generate API

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/maa.i

@@ -3,7 +3,7 @@
     #include "gpio.hpp"
     #include "pwm.hpp"
     #include "i2c.hpp"
-    #include "spi.h"
+    #include "spi.hpp"
     #include "aio.hpp"
 %}
 
@@ -29,37 +29,7 @@ const char * maa_get_version();
 
 #### SPI ####
 
-%rename(Spi) maa_spi_context;
-
-%ignore spifd;
-typedef struct {
-    /*@{*/
-    int spifd; /**< File descriptor to SPI Device */
-    /*@}*/
-} maa_spi_context;
-
-%nodefault maa_spi_context;
-%extend maa_spi_context {
-  maa_spi_context()
-  {
-    return maa_spi_init();
-  }
-  ~maa_spi_context()
-  {
-  }
-  int mode(unsigned short mode)
-  {
-    return maa_spi_mode($self, mode);
-  }
-  int frequency(int hz)
-  {
-    return maa_spi_frequency($self, hz);
-  }
-  unsigned int write(unsigned int data)
-  {
-    return maa_spi_write($self, data);
-  }
-}
+%include "spi.hpp"
 
 #### AIO ####