Add configuration option for ghost reset distance. Improve documentation.

collisions.h

@@ -3,6 +3,7 @@
 
 #include <glm/glm.hpp>
 
+// Returns 1 if the segment (vec_start -> vec_stop) intersects triangle (P1,P2,P3).
 int get_intersection(glm::vec3 vec_start, glm::vec3 vec_stop, glm::vec3 P1, glm::vec3 P2, glm::vec3 P3);
 
 #endif