Solve import order problem when POULibrary imports ConfigTreeNode because of UserAddressedException. Now UserAddressedException is declared in POULibrary.py, as a quick and dirty fix, but some independant module should be created for beremiz exceptions in general.

Beremiz's user manual
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Contents:

.. toctree::
   :maxdepth: 2

   install
   start
   edit
   build
   connectors
   debug