- separates node-based graph creation and compression from edge-based graph creation
- moves usage of edge-based node data-container to pre-processing as well, unifying access to node-based data
- single struct instead of separate vectors for annotation data in engine (single place of modification)
https://github.com/Project-OSRM/osrm-backend/pull/2685/files
fixes an issue where we did
elongate(fstStep, sndStep);
instead of
newStep = elongate(fstStep, sndStep);
we didn't get any warnings.
The only way to trigger a warning here is to use
```cpp
__attribute__((warn_unused_result))
```
This changeset does exactly that: for the new guidance code prone to
these kind of issue we add such an attribute to the declaration.
