Darwin robot driver smart charger

Added two functions to check if smart charger if detected and enabled.
Modified functions to access them with doubles (time in seconds and Amperes).

In terminal:
 -Default period of the smart charger and new period
 -Smart charger detected, not detected or detected and enabled
 -Start motion manager (if smart charger detected and enabled, it will execute the read operations)
 -Battery status: connected, disconnected or connected and charging
 -Shows average time to full and to empty in min (65535 it means -1)

Functions to access the smart charger module has been added to the driver of the Darwin robot.
Allows to enable or disable module, set and get period, get smart charger's data (average time to empty and to full
and battery status), read smart charger's control register (smart charger detected and/or enabled), write limit current.