Provide line and ray types

[MarcelloPerathoner]

Many geometric algorithms use a "line sweep" or "plane sweep" or a rotating "ray sweep". Eg. often used in polygon trapezoidation, Voronoi, visibility graph.

Please provide these two data types:

• line, extending infinitely in both directions,
• ray, extending inifinitely in one direction only,

and intersection algorithms for them.

[barendgehrels]

Moved from Issue to Idea.
Lines are already there, but it is internal and there are not yet many algorithms.

[tinko92]

This raises some questions about the intended scope of Boost.Geometry and the delineation to Boost.Polygon which has Voronoi diagrams and adaptors to Boost.Geometry (but no rays and lines and I don't know how maintained it is). The main development certainly seems motivated by GIS applications and the types cover OGC Simple Features, which do not include rays and infinite lines. Having said that, I used it for ECAD applications.

It would bring up some other questions as well, e.g. what is a ray in geographic coordinates and what is a the WKT representation of a line and a ray.