Duplicate restriction nodes in the edge-based-graph are currently
not in included in a mapping (.osrm.cnbg_to_ebg) from
node-based-graph edges to edge-based-graph nodes.
This mapping is used by the MLD partitioner to assign EBG nodes
to partitions.
The omission from the mapping means all restriction nodes are
included in a special 'invalid' partition. This special partition
will break the geolocation properties of the multi-level hierarchy.
The partition and its super levels will have a large number of
border nodes and very few internal paths between them.
Given the partitioner is the only consumer of the mapping, we fix
the issue by including the duplicate restriction nodes in the mapping,
so that they are correctly assigned to a partition.
This has measurable improvement on MLD routing.
For a country-sized routing network, the fix reduces routing and table
request computation time by ~2% and ~6% respectively.
Make entry points of individual pipeline stages responsible for
configuring the task scheduler with requested number of threads
passed in corresponding configuration bundle (ie. follow extractor).
Rename module partition to partitioner.
This cultivates naming used in existing modules like extractor,
customizer, etc. - noun vs verb (word partition is both though).
