[cpp][py] Expose sensor.bin_data attrbute

[ddemidov]

This provides user access to bin_data_format/bin_data attributes of sensor class in C++ and python. See ddemidov/ev3dev-lang-python#4.

In C++ its possible to ask the sensor to read raw data into a user-supplied buffer/struct:

struct  __attribute__((__packed__)) abs_imu_data {
  char tilt[3];
  short accel[3];
  short compass;
  short mag[3];
  short gyro[3];
} val;

// The get_bin_data is implemented as template:
gyro.get_bin_data(&val);

In python, sensor.bin_data() function either returns a byte buffer, or unpacked tuple:

>>> from ev3dev import *
>>> ir = infrared_sensor()
>>> ir.value()
28
>>> ir.bin_data()
<read-only buffer ptr 0x3f6a58, size 1 at 0xb6a12b00>
>>> ir.bin_data('<b')
(28,)