i2c.hpp: add read(size_t length) function useful in scripting languages

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

api/mraa/i2c.hpp

@@ -98,6 +98,18 @@ class I2c {
         int read(char * data, size_t length) {
             return mraa_i2c_read(m_i2c, (uint8_t*) data, (int) length);
         }
+	/**
+	 * Read length bytes from the bus, this function will allocate memory
+	 * and will require you to free the returned pointer
+	 *
+	 * @param length Size of read to make
+	 * @return pointer to read data which must be freed
+	 */
+        uint8_t* read(size_t length) {
+            uint8_t* data = (uint8_t*) malloc(sizeof(uint8_t) * length);
+            mraa_i2c_read(m_i2c, data, (int) length);
+            return data;
+        }
         /**
          * Write one byte to the bus
          *