Add item attribute what prevent item removing on use.

New item attribute: KeepAfterUse
Merge pull request #397 from 4144/nodelonuse

Add item attribute what prevent item removing on use.
in validateinterfaces.py tool add support for checking not added functions to initerfaces.
Add different command line actions to validateinterfaces.py.
Improve a bit checking in validateinterfaces.py.
Replace some direct methods usage to interfaces.