Refactor sensors file

[simonedegiacomi]

The ev3_sensor.c file is very long and it contains all the logic to initialize and read raw values from sensors and to convert the raw values to the needed ones.

I think that this file needs a refactor to:

• separate the logic to convert raw values of each sensor;
• avoid the need to continuously jump between the start and the end of the file when updating/adding a new sensor;

One idea that comes to my mind is to create a ev3_sensors folder and have a file for each sensor. Then, each file would have functions with logically similar names (init_compass, init_touch, read_compass, read_touch, set_compass_mode, etc...)

[simonedegiacomi]

• move function to read sensor from ev3_sensor.c to a file for each sensor
  • touch
  • ev3 ir
  • ht ir
  • ev3 color
  • ev3 ultrasonic
  • ev3 gyro
  • ev3 ir
  • nxt temperature
  • nxt sound
  • ht compass
• move the sensor initialization to files for each sensor