Standardize trace_particle_through_mesh

[Fuad-HH]

• [x] Replace ray_intersects_triangle with line_segment_intersects_triangle.
• [x] Standardize* the behavior of arrays used as parameters.
• [x] Move set_new_element function inside the functor.
• [x] Add next_element parameter that holds the next element and passes to the functor.
• [x] Fix closeness algorithm in find_exit_face
• [x] Add test case for search_mesh

*After adding the callback functor, it is necessary for the user to know a clearly defined meaning of the particle state arrays.

[Fuad-HH]

@jacobmerson I will keep it draft until I bring the test case here. But please start reviewing the changes. I will commit the new test case for search_mesh and some other small changes later, maybe after we discuss them. The changes are based on master and #142 is not merged yet here.