Buffs mecha weapons and more (#4269)

-separates the mecha weapons dmi in three different dmis for each type of weapon
-buffs the ion cannon, by having its ion being 5x more effective than the regular ion gun
-buffs the damage from the mecha smg
-adds new weapons such as the gatling laser, gatling xray, mounted tesla cannon, mounted anti-material rifle, mounted gyrojet autocannon, mounted anti-material cannon and possible more
-increases the equipment slot for mechas to 4 from 3
-adds some of the new weapons design to the mech fabricator
-changes the weapons names to be more generic

code/modules/projectiles/projectile/beams.dm

@@ -66,6 +66,18 @@
 		target.ex_act(2)
 	..()
 
+/obj/item/projectile/beam/pulse/heavy
+	name = "heavy pulse laser"
+	icon_state = "pulse1_bl"
+	var/life = 20
+
+/obj/item/projectile/beam/pulse/heavy/Bump(atom/A)
+	A.bullet_act(src, def_zone)
+	src.life -= 10
+	if(life <= 0)
+		qdel(src)
+	return
+
 /obj/item/projectile/beam/emitter
 	name = "emitter beam"
 	icon_state = "emitter"

code/modules/projectiles/projectile/special.dm

@@ -15,6 +15,10 @@
 	name = "ion pulse"
 	pulse_range = 0
 
+/obj/item/projectile/ion/heavy
+	name = "heavy ion pulse"
+	pulse_range = 5
+
 /obj/item/projectile/bullet/gyro
 	name ="explosive bolt"
 	icon_state= "bolter"
@@ -175,6 +179,18 @@
 	damage_type = HALLOSS
 	muzzle_type = /obj/effect/projectile/bullet/muzzle
 
+/obj/item/projectile/bullet/cannon
+	name ="armor-piercing shell"
+	icon = 'icons/obj/grenade.dmi'
+	icon_state = "shell"
+	damage = 90
+	armor_penetration = 80
+	penetrating = 1
+
+/obj/item/projectile/bullet/cannon/on_impact(var/atom/A)
+	explosion(A, 2, 3, 4, 4)
+	..()
+
 //magic
 
 /obj/item/projectile/magic