Add new Arduino code that sends directly the raw values of all 9 sensors
with milliseconds timestamps and then with microseconds timestamps.

Add three new sampled data files
1. new_test_usec: 
Timestamp in microseconds with raw (uncalibrated) accelerometer sensor
value in x,y,z in the inertial ref of the mobile platform, same for
magnetometer and gyroscope.
The board was placed on the table and rotated +90 and then -90 degrees
around its three axes, slowly

2. new_usec_3hits
Same, but with 3 direct punches, 3 hooks and 3 uppercuts

3. new_millis_3hits:
Same, but timestamp in millis