Enables Random borer event

Enables the borer event, from max 0 occurances to max 1 occurance per
round.
Decreases random chance weight of borer event, from 15 down to the
default 10.
Increases minimum players required up from 15 to 20, as the gamemode at
MINIMUM requires 10 living players to greentext anyway and does poorly
on very lowpop rounds.
Earliest start increased from 20 minutes to 40 minutes, as our rounds
lasts longer than TG rounds do.

code/game/gamemodes/miniantags/borer/borer_event.dm

@@ -1,10 +1,9 @@
 /datum/round_event_control/borer
 	name = "Borer"
 	typepath = /datum/round_event/borer
-	weight = 15
-	max_occurrences = 0
-	min_players = 15
-	earliest_start = 12000
+	weight = 10 //Default weight
+	max_occurrences = 1
+	earliest_start = 24000 //40 min, double default timer
 
 /datum/round_event/borer
 	announceWhen = 2400 //Borers get 4 minutes till the crew tries to murder them.