added particle direction to point_in_volume call
switch link order
broke the process, but seems more correct, argh!
added new function to prove we are where we say we are
removed lkwr function from g1_fire and added dir to point_in_volume
Add comments; initialize is_inside
Merge pull request #84 from svalinn/point_in_volume_issue_78

added particle direction to point_in_volume call