Fixes robot stacks transferability

Cleans up transferring between stacks and makes robot stacks
transferable with regular ones.
Stack reorganization, use() now dels after yield

stack/use() now only deletes an empty stack after the current context
yields, removing the need for some awkward patterns when dealing with
stacks. Also adds procs for transferring and splitting stacks.
Adjusts door repair to use a welding tool
Added proc for can_shred() on robots.
Fixed brain transplant issue.
Added xenomorph exclusions to space suits and helmets.
Fixed incorrect role check on leap().
Fixed incorrect cuff resist time when species with can_shred() resisted.
Typo from robotslash commit.
NO_PAIN will now properly stop hard stun from taking effect.
Extremely minor runtime fix.
Amending stun commit.

Stun will properly be set to 0 if the species has NO_PAIN.
Fixes #7327
Fixes #7431
Overhauls SSD mechanic.
Merge branch 'dev-freeze' of https://github.com/Baystation12/Baystation12 into essEssDee
Merge pull request #2 from Baystation12/dev-freeze

Dev freeze
Merge branch 'dev-freeze' of https://github.com/Ravensdale/Baystation12 into essEssDee
Corrected oversight
Fixes a comment, bleh.