Now we always jump to PAYLOAD_SWITCHING_OFF state before going to
PAYLOAD_NO_POWER, this way we can safely turn off the payload and warn
the MCH about the failure

Now each sensor must call sdr_insert_entry() upon initialization to
include its sensors in the SDR table.
The SDR table cals realloc each time a new entry is requested, so it
doesn't use unnecessary memory.

INA220 SDR was put in a different source file (ina220_sdr.c) because
it's too large and would polute the original source (ina220.c)

The comparation would work if the SENSOR_STATE_NORMAL wasn't equal to 0,
which invalidates the statement.
Now checks each state a time.

As stated in PCA9547 datasheet:
The fourth bit in the control byte must be set to one in order to enable
the access to the selected channel

Also format the whole file

FMC1 and FMC2 had their channels switched

Fixes #21

Fix for last commit

Since temperature changes slowly, we'll be fine with 2Hz update rate