*Small tidy-up of various helper procs*

-Turns out there was already a Gaussian PRNG proc already, used by mechs and turrets. I've replaced it with my one as mine has almost half the cost. (currently broken! still waiting for fixes to be pulled!)
-replaced between(min, val, max) with Clamp(val, min, max)
-get_turf(thing) now uses var/list/locs to locate its turf, rather than iterating up through loc of its loc of its loc...etc
-sign(num) moved to maths.dm
-InRange(val, min, max) replaced with IsInRange(val, min, max) (they were identical)
-Removed ismultitool() iswrench() iscoil() iswire() iswelder() iscrowbar() etc
-removed modulus(num) as abs() performs the same task! *roll-eyes*
-removed get_mob_with_client_list() as it is no longer needed (we have var/list/player_list now)
-removed get_turf_or_move() as it simply called get_turf
-removed get_turf_loc() as it was identical to get_turf()

*Additions:*
-The "Declare Ready" link in the lobby will automatically become "Join Game" if the round starts before you declare ready, so you don't have to click it twice

Not tested properly as I'm horrifically tired - so there'd be no point.
I'll test it later and comment.