Fixes object icons not being updated when refitting hardsuits for different species

If this should go to dev instead, let me know.

* Adds a generalized system for refitting clothing, that updates object sprites according to specified sprite sheets in obj/clothing/species/
* Makes engineering hardsuits a subtype of a parent rig type, so that engineering hardsuits can be updated without modifying every other hardsuit type.
* Fixes several issues with modkits

Note that I could only find sprites for tajaran engineering hardsuits, and syndie hardsuits for tajaran, skrell, and unathi, so those are the only items that have alternate sprites at the moment. I think Unity station has a wider range of tajaran hardsuit sprites, we might be able to get some from there.
I just realized that this switch block will allow skrell to wear helmets fitted for humans, while preventing humans from wearing helmets fitted for skrell, the opposite of what was intended.