Refbox OPC-UA communication

[morxa]

Replace the communication to the MPS machines with a OPC-UA communication based on open62541.

For testing, use the mockup developed in robocup-logistics/rcll-mps-stations#1.

[morxa]

The open62541 library is available on Fedora. I started to co-maintain the package to make sure that the package is in good shape. I also updated the package to the latest release.

[timn]

You should also check Ubuntu or provide a PPA (similar to my CLIPS PPA). We had Ubuntu installed on the provided referee box machines a couple times in the past.

[morxa]

As discussed yesterday in a meeting, we will first merge the current master into new-mps-communication and start working from there. This allows us to use the new communication protocol between refbox and MPS stations and directly implement OPC-UA communication with the new protocol instead of replacing modbus with OPC-UA in the old protocol.

For this, I first want #16 to be merged into master, as it may bring additional conflicts.