Currently, to_chat is literally just a proc that does user << message.
But it'll let us do output modification in the future, especially for
something like Goon's HTML chat.
Big thanks to PJB for his to_chat script, see
https://github.com/d3athrow/vgstation13/pull/6625 for more details.
This commit does the following:
- Replaces all instances of magic intent words, like "harm" and
"help" with defines, I_HELP, I_DISARM, I_GRAB, I_HARM
- Fixes a few manual grab instances left over in attack_alien, they
will now used grabbedby()
