Standardizing attack messages to always show the attacker first

Standardizes attack messages to always show the attacker first(when there is an attacker). (see poll at https://tgstation13.org/phpBB/viewtopic.php?f=9&t=1903)

Replacing some fo mob in viewers() show_message() with visible message().
Simplifying some message code in a couple places, fixing typos and span classes.

Not sure if this counts as a feature.