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

Library/OSRM_impl.cpp

@@ -28,6 +28,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "OSRM_impl.h"
 #include "OSRM.h"
 
+#include "../Plugins/DistanceTablePlugin.h"
 #include "../Plugins/HelloWorldPlugin.h"
 #include "../Plugins/LocatePlugin.h"
 #include "../Plugins/NearestPlugin.h"
@@ -55,6 +56,7 @@ OSRM_impl::OSRM_impl(const ServerPaths &server_paths, const bool use_shared_memo
     }
 
     // The following plugins handle all requests.
+    RegisterPlugin(new DistanceTablePlugin<BaseDataFacade<QueryEdge::EdgeData>>(query_data_facade));
     RegisterPlugin(new HelloWorldPlugin());
     RegisterPlugin(new LocatePlugin<BaseDataFacade<QueryEdge::EdgeData>>(query_data_facade));
     RegisterPlugin(new NearestPlugin<BaseDataFacade<QueryEdge::EdgeData>>(query_data_facade));