Add bearing filter support to viaroute, trip, nearest, and distance

table plugins.
Make bearing range configurable by adding a comma-separated second part
to the bearing paramenter, like so:

    b=<bearing:0-359>(,<range:0-180>)

If no range is supplied, it defaults to +/- 10 degrees.

include/osrm/route_parameters.hpp

@@ -72,7 +72,7 @@ struct RouteParameters
 
     void addTimestamp(const unsigned timestamp);
 
-    void addBearing(const int timestamp, boost::spirit::qi::unused_type unused, bool& pass);
+    void addBearing(const boost::fusion::vector<int, boost::optional<int>> &received_bearing, boost::spirit::qi::unused_type unused, bool& pass);
 
     void setLanguage(const std::string &language);
 
@@ -102,7 +102,7 @@ struct RouteParameters
     std::string language;
     std::vector<std::string> hints;
     std::vector<unsigned> timestamps;
-    std::vector<int> bearings;
+    std::vector<std::pair<const int,const boost::optional<int>>> bearings;
     std::vector<bool> uturns;
     std::vector<FixedPointCoordinate> coordinates;
 };