Fixes #7807 and a bunch of Mixed Mode + Cult related issues
Created by: DeityLink
Who the heck even added Cult to Mixed Mode anyway? I mean it's cool but there's a lot of things to check so you don't mess up objectives and stuff.
On that note, I added a new proc is_round_cult() that either returns ticker.mode if the round is cult, or the cult mode inside ticker.mode.modes if the round is mixed with cult, or null if the round has no cult going on at all. So from now on instead of doing
if(ticker.mode.name == "cult")
you do
var/datum/game_mode/cult/cult_round = is_round_cult()
if(cult_round)
etc
Also fixed a weird issue about blood cleanables and DNA.
Oh and lastly, /datum/admins/proc/check_antagonists() was taking half of player_panel.dm and I could never find it when I needed it so I moved it to its own new file. And fixed a typo in it.