remove/tone down the obnoxious green overlay on mesons

[Mordent]

Yeah, as-is it's definitely overkill (to the point of me using mesonic cybereyes as a way of messing with people as an antag).

There's a suggestion to make it able to be toggled on/off, which would at least half-solve it, but the level of green could be made less extreme (consider halfway between a gas mask and current implementation - still a very strong green filter but not actually painful).