User can specify list of route attributes in the configuration file
and run route aggregation on the export side of the pipe protocol.
Routes are sorted and for every group of equivalent routes
new route is created and exported to the routing table.
It is also possible to specify filter which will run for every
route before aggregation.
Furthermore, it will be possible to set attributes of new routes
according to attributes of the aggregated routes.
This is a work in progress.
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