Implemented Fw update over FoE

[XzuluX]

Implemented firmware update for slave device.

Enhanced wrapper with functionality to set mailbox configuration for specific slave in order to download firmware file over FoE. Firmware update functionality has been verified with Beckoff Slave EL3021.
Implemented also functions to trigger slave state transition to new state and read current slave state.

[Apollo3zehn]

Thanks for that useful PR. However, could you please raise it against the dev branch? Thanks :)

[XzuluX]

I rebased it to dev branch, so it's on the top of dev. Do you mean that with raise against dev?

[Apollo3zehn]

No, sorry I mean this

You want to merge into master, but I would prefer if you could change it to dev. Thank you!

[Apollo3zehn]

Thanks again, looks very good. There is only one thing I think should be changed: You have renamed RequestOpState to RequestCommonState. But RequestOpState is specific to the OP state because it contains

ecx_send_processdata(context);
ecx_receive_processdata(context, EC_TIMEOUTRET);

I think we could instead rename the CheckSafeOpState method which does exactly what I think you indent with RequestCommonState and let RequestOpState untouched.

[Apollo3zehn]

Sorry, I was wrong, CheckSafeOpState is really just a check. Maybe we can instead change the code of RequestCommonState to skip the processdata methods for states other than "OP".

[XzuluX]

Thank's for reviewing my PR! I changed RequestCommonState and now the processdata methods are only performed if current state is OP.