bump variant dependency
remove inline keywords
To arrive at a later point in time: Revert "remove inline keywords"

This reverts commit 81b0447024921899b3d80fc2435efe2b09f9fd3a.
some minor include untangling
add range-based for_each_pair
Refactor routing plugins:

- remove superflous members from RawRouteData, partially implements #1238
- DescriptorTable moved to BaseDescriptor.h
- added templated assignment c'tor to DescriptorConfig
- refactored check for valid input coordinates, moved to BasePlugin.h
- replaced shared_ptr's to descriptors in ViaRoutePlugin.h with unique_ptr
- implemented FindIncrementalPhantomNode in facades for a single, i.e. first result
- untangled a few includes
remove superflous include from library
add benchmark for a single coordinate incremental lookup
disable debug code in rtree
untangle includes
add libosmium
remove legacy extrators
implement restriction parsing
implement restriction parsing
implement ExtractionWay and -Node
remove explicit keyword from WayIDStartAndEndEdge ctor
implement new Restriction type
add include dir to libosmium
implement loader routines for new restriction type
support new restriction type in component analysis