Porting /tg/'s attack animation. Also fixes some typos, message styling and capitalisation.

See https://github.com/tgstation/-tg-station/pull/5642 for more details on animation.

Example:
![image](https://cloud.githubusercontent.com/assets/3803177/4983396/98a0b9da-691a-11e4-9f79-9f071ed091e4.png)