Maik JUSTUS:

Maik JUSTUS:

"""
- make every node maintain list of properties that link to it
- add functions to erase node by address from hash bucket/entry in their
  path caches, so that all references can be removed
- if a node is removed, it (and all children, grandchildren, ...) calls
  all linked properties to remove them from their path-cache

This fixes problems with the aerotow over multiplayer and maybe some
other problems, where nodes are queried by name.
"""