Refactoring. Separated PLC Object, PYRO Server and MainWorker :
- PLC Object is now a Singleton, instantiated through runtime.CreatePLCObjectSingleton(...)
- Pyro server doesn't hold any reference to PLCObject, and doesn't create it anymore
- PLC Object class doesn't inherit from Pyro.ObjBase anymore
- Pyro related code moved to runtime.PyroServer.py
- MainWorker class moved to runtime/Worker.py
- Both PLC Object and MainWorker creation happens in runtime/__init__.py

<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot URI_location="LOCAL://">
  <TargetType/>
  <Libraries Enable_Native_Library="true"/>
</BeremizRoot>