fix regression in debug build
Simple fix that improves runtime of edge based egde generation by 26%
Add atan based on lookup table. Again 6% improvement.
Merge branch 'TheMarex-atan-perf' into develop
remove boost::thread from Server
use std::packaged_task and std::future to simulate boost::thread::timed_join()
minor reformatting
add parantheses to fix compiler warning
use std::abs instead of hand-rolled substitute
leave early to reduce scope nesting
remove whitespace
move common code into its own header
use range based for loops to traverse graphs
reorder some includes
rename variables
deactivate LTO on debug build
add test for roundabout with oneone links
add simple isValid() function to PhantomNodes
implements output generation through a dedicated JSON container:

- JSON syntax is not scattered over several files, but one place
- Reduces code duplication
- breaking changes:
  - new property in json(p) formatted response: "found_alternative": True/False
  - returned filenames now response.js(on) or route.gpx
  - /hello plugin returns JSON now
adapt JSON parsing in tests to allow for omitted fields