Fix for issue #94.
Gorge web strands now have hit detection which matches their visible component. This is for both ensnaring marines, and for cutting them with a welder.
This has the following impacts:
* Webs are easier for marines to avoid since they can safely jump or duck under angled strands, however...
* Webs are harder for marines to cut as they can no longer clear a while corridor with a single click but have to actually aim at each strand
