Resolve "Exponential NodeOpcUA growth"

Summary

Currently the opc_path attribute of NodeOpcUa creates an exponential amout of child nodes.

Also why does the Connection need a create_nodes method? It doesn't seem reasonable to create nodes on a server by the connection.

Explain your context

(Explain what you did.)

Please list breaking changes, new features or bugfixes

• Breaking changes:

  • Deprecate create_nodes and delete_nodes from the OpcUaConnection
  • Deprecate opc_path attribute from NodeOpcUa

• New features:

• Bugfixes:

Closes #321 (closed)