eb_pwr: New version of power management.

eb_pwr: New version of power management.

- time measurement using global variable with time
Now time is measured in the same manner as in the other modules (ie. eb_vidle atc).
The code is more clear ant later improvements are easier.

- I have moved all the definitions to header files, add def.h file.
This improves clarity and readability.

- Now 5V and 3.3V power supply is switched off only when battery is in critical state.
Prevents cyclic on/off switching of all the boards in the robot.

Still this algorithm needs improvements, but now CAN communication is more reliable.