https://github.com/open62541/open62541

License: LGPLv3, with static linking exception. To update (from an
open62541 checkout):

cmake -D UA_ENABLE_SUBSCRIPTIONS=ON -D UA_ENABLE_AMALGAMATION=ON .
make -j2
cp open62541.{c,h} /path/to/3rdParty/open62541/

We only include the single c/h-file in order to not include
documentation, etc.
