Bools and returns super-pr (#53221)

Replaces like 70-80% of 0 and such, as a side effect cleaned up a bunch of returns
Edit: Most left out ones are in mecha which should be done in mecha refactor already
Oh my look how clean it is

Co-authored-by: TiviPlus <TiviPlus>
Co-authored-by: Couls <coul422@gmail.com>

code/modules/admin/callproc/callproc.dm

@@ -130,7 +130,7 @@ GLOBAL_PROTECT(LastAdminCalledProc)
 /client/proc/callproc_datum(datum/A as null|area|mob|obj|turf)
 	set category = "Debug"
 	set name = "Atom ProcCall"
-	set waitfor = 0
+	set waitfor = FALSE
 
 	if(!check_rights(R_DEBUG))
 		return