Refactor routing plugins:

- remove superflous members from RawRouteData, partially implements #1238
- DescriptorTable moved to BaseDescriptor.h
- added templated assignment c'tor to DescriptorConfig
- refactored check for valid input coordinates, moved to BasePlugin.h
- replaced shared_ptr's to descriptors in ViaRoutePlugin.h with unique_ptr
- implemented FindIncrementalPhantomNode in facades for a single, i.e. first result
- untangled a few includes

Descriptors/BaseDescriptor.h

@@ -35,13 +35,35 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <osrm/Reply.h>
 
 #include <string>
+#include <unordered_map>
 #include <vector>
 
+
+struct DescriptorTable : public std::unordered_map<std::string, unsigned>
+{
+    unsigned get_id(const std::string &key)
+    {
+        auto iter = find(key);
+        if (iter != end()) 
+        {
+            return iter->second;
+        } 
+        return 0;
+    }
+};
+ 
+
 struct DescriptorConfig
 {
     DescriptorConfig() : instructions(true), geometry(true), encode_geometry(true), zoom_level(18)
     {
     }
+
+    template<class OtherT>
+    DescriptorConfig(const OtherT &other) : instructions(other.print_instructions), 
+                                            geometry(other.geometry), 
+                                            encode_geometry(other.compression), 
+                                            zoom_level(other.zoom_level) { }
     bool instructions;
     bool geometry;
     bool encode_geometry;

Descriptors/JSONDescriptor.h

@@ -278,7 +278,7 @@ template <class DataFacadeT> class JSONDescriptor final : public BaseDescriptor<
         }
 
         JSON::Object json_hint_object;
-        json_hint_object.values["checksum"] = raw_route.check_sum;
+        json_hint_object.values["checksum"] = facade->GetCheckSum();
         JSON::Array json_location_hint_array;
         std::string hint;
         for (const auto i : osrm::irange<std::size_t>(0, raw_route.segment_end_coordinates.size()))