Plastic kevlar repair + fur repair fix

Fixed the underscore issue in the new kevlar/plastic repair. Added metal repair with scrap metal.

Moved all plastic/kevlar/metal repair and modification functions to iuse::solder_weld() and changed soldering iron to use the new function. solder_weld() still allows cauterization like before, but now you can select repair/modification as well.

Both iuse::sew and iuse::solder_weld now take into account both materials for a repair target. Before, you couldn't repair a fur item with fur, since the sew function would see the fur item has a leather material, try to find leather and then fail without ever trying to look for fur. It now looks for both types of repair item before failing.