Split esc (ethercat slave controller) code into seperate modules.
Add code to read SII eeprom of esc devices and use it for
device initialization.
Add per device thread for monitoring/recovery of devices.

Also some changes to properly log to console when no slaves are found

A few improvements from the Vitsch Electronics CVS
Use log_send() for all logging and add context (DEBUG/WARNING/ERROR) info.
A little bit more comments

Mostly ethercat related in the ec directory.

Also fix some reentrancy issues in the controller_load functions.