[MERGED PR] Some traitor objective wording adjustments and slight code cleaning

[BatElite]

For clarity, the wording changes (in bold) as they'd be ingame are:

Assassination: append "It doesn't count if they get revived, unless it's as a cyborg/AI." after the random fluff text (E.G. "for doing X" or "and make sure to Y")

Stealing: "Steal the [target_name] and have it anywhere on your person at the end of the shift."

Multi-steal:
-For hearts: "You're a real Romeo! Steal the (literal) hearts of [multigrab_num] crewmembers and have them all anywhere on your person at the end of the shift."
-Anything else: "Steal [multigrab_num] [target_name] and have them all anywhere on your person at the end of the shift."

Solo hijack: "Hijack the emergency shuttle by escaping alone. If someone else did sneak on, make sure they are dead before reaching Centcom."

Survive: "Stay alive until the end of the shift no matter if you're on station or not."

Rescue: "Ensure that [target.current.real_name], the [target.assigned_role], safely arrives at Centcom alive and not as a cyborg."

Group hijack: "Hijack the emergency shuttle by escaping alone or with your accomplices. Anyone else who snuck on needs to be dead before reaching Centcom."

I'm kinda supposed to be doing other stuff so I don't want to get into thinking of alternative phrasing right now, my general thoughts are that all these changes are sensible clarifications but the wording tends to be a bit awkward.