This PR adds more advanced coordinate extraction, analysing the road
to detect offsets due to OSM way modelling.
In addition it improves the handling of bearings. Right now OSM reports
bearings simply based on the very first coordinate along a way.
With this PR, we store the bearings for a turn correctly, making the
bearings for turns correct.
With @karenzshea's name / ref split (ref. #2857) in master we want to
make use of it and reduce `NewName` instructions when ever possible.
This is a first step towards #2744 by using the already existing name
change heuristic from the extractor now in post-processing as well.
Limitations: at the moment we don't have the `SuffixTable` in
post-processing; this would require us serializing and subsequently
deserializing the table, passing it through from the profiles to the
API.
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.
