fixed leaving out a time summand
implemented (didn't test) actually inserting events

It overflows immediately if you try to run it
Implemented (compiles, didn't test) checks for...

...whether the "collisions" between vertices/lines/
   /planes actually are correct (within the face/
   /segment) or only true when the planes/edges
   are extended to infinity.

These checks currently allow rounding error that will
   screw things up. They're a prototype.