[algorithms][distance] add dispatch for the ring/ring combination
[algorithms][distance] add dispatch for the three multigeometry-to-ring combinations
[test][distance] add include for rings
[algorithms][distance] add test cases for the point/ring and multipoint/ring combinations
[test][distance] add test cases for the segment/ring and linestring/ring combinations
[test][distance] add test cases for the multilinestring/ring combination
[test][distance] add test cases for the combinations: polygon/ring,
multipolygon/ring, ring/ring and ring/box
Merge pull request #91 from mkaravel/feature/distance

Feature/distance