Plant Age, Weeds, and Pest Tweaks

Makes plants die when they get old again.
- Plants begin dying once they age past 5 times their TRAIT_MATURATION
value.
- This means a plant with TRAIT_MATURATION 5 will begin dying when it
reaches age 26 and higher
- Plant death will occur over time as it loses health each process.
- Can be slightly deferred with health restoring reagents, but is
unavoidable in the long run.

Weed growth in trays has been returned to pre-#980 chances.
- Chance for weedLevel to increase is 6% if no seed planted, 3%
otherwise
- With #980, this was unintentionally dropped to 5% / 1%

Pest growth in trays has received a buff
- Now a 5% chance per process to increase pestLevel by 0.5
- Previously was 3% chance to increase by 0.1
- Pre-#980, this was a 3% chance to increase by 1.0

code/modules/hydroponics/trays/tray_process.dm

@@ -19,7 +19,7 @@
 
 	// Weeds like water and nutrients, there's a chance the weed population will increase.
 	// Bonus chance if the tray is unoccupied.
-	if(waterlevel > 10 && nutrilevel > 2 && prob(isnull(seed) ? 5 : 1))
+	if(waterlevel > 10 && nutrilevel > 2 && prob(isnull(seed) ? 6 : 3))
 		weedlevel += 1 * HYDRO_SPEED_MULTIPLIER
 
 	// There's a chance for a weed explosion to happen if the weeds take over.
@@ -110,6 +110,11 @@
 			health -= HYDRO_SPEED_MULTIPLIER
 
 	// Handle life and death.
+	// If the plant gets too old, begin killing it each cycle
+	var/lifespan = 5 * seed.get_trait(TRAIT_MATURATION)
+	if(age > lifespan)
+		health -= rand(5,10) * HYDRO_SPEED_MULTIPLIER
+
 	// When the plant dies, weeds thrive and pests die off.
 	check_health()
 
@@ -120,8 +125,8 @@
 		harvest = 1
 		lastproduce = age
 
-	if(prob(3))  // On each tick, there's a chance the pest population will increase
-		pestlevel += 0.1 * HYDRO_SPEED_MULTIPLIER
+	if(prob(5))  // On each tick, there's a chance the pest population will increase
+		pestlevel += 0.5 * HYDRO_SPEED_MULTIPLIER
 
 	// Some seeds will self-harvest if you don't keep a lid on them.
 	if(seed && seed.can_self_harvest && harvest && !closed_system && prob(5))