configure turn cost calculation

[karussell]

Fixes #1590.

Use cases:

• avoid left turns for motor vehicles
• avoid zig zag routes e.g. for bike like described in Prefer cycleway=lane for bike #1500.
• exclude too sharp turns for e.g. trucks set sharp_left_turn_costs and sharp_right_turn_costs to very high values.
• if straight_costs gets a value you can avoid dense areas via avoiding too many junctions. As the ETA is unaffected this is similar to a custom model that reduces priority for urban_density==CITY.

Some of the configuration details are stated in core/src/main/resources/com/graphhopper/custom_models/bike_tc.json

Note that there are the following different angles:

• for 0° until +-min_angle => turn costs is straight_costs (default is 0)
• for min_turn_angle until min_sharp_angle => turn costs is left_turn_costs (default is 0)
• for min_sharp_turn_angle until min_u_turn_angle => turn costs is sharp_left_turn_costs (default is 0)
• for bigger than min_u_turn_angle => turn costs is u_turn_costs

Note:

• left_turn_costs and right_turn_costs are symmetric
• default min_turn_angle=25
• default min_sharp_turn_angle=80
• default min_u_turn_angle=180

The implementation fills an orientation encoded value where the forward value stores the orientation of the end segment of the edge and the backward value stores the orientation of the start segment of the edge. With that all turn angles can be calculated. Of course sometimes a "left turn" cannot be detected from the angle alone and topology must be considered but for now this orientation approach works good enough (and the topology approach did not work that well alone when I tried it before).

A more sophisticated implementation could also use different turn costs depending on the country or road_class but this and a request-based customization of the turn costs (moving it into the custom_model) should not be part of this PR.