Standardizes and cleans up objective.dm
Converts Steal objectives (except for blueprints grr) to a datum-based system. This is to support further changes to the objective system, though it does make adding new objectives nice, simple and compartmentalized.
Completes code changes; reimplements ninja steal objective.
Merge branch 'master' of https://github.com/tgstation/-tg-station into objectives
Gets rid of a couple colons.
Merge pull request #2545 from Cheridan/objectives

Objective Refactor