Execution/gunpoint shots work properly with pellet clouds, buffs piercing wounds a bit (#52995)

Made a few changes to gunpoints and some related mechanics while tidying up and adding docs. Here's a quick list

-Execution (point blank help intent shot aimed at the mouth) and gunpoint shots now apply their bonuses to every pellet fired rather than only the first, generally making them gushier. They also buff wound power as well as damage
-You can no longer punch yourself while holding someone up to trigger the charged shot
-You can no longer purposely fail executions and gunpoints with pax or whatever to endlessly spike the damage in a loaded round
-Attacks with extremely high wounding power can now outright dismember limbs regardless of mangled status. The threshold is high enough that it mostly applies for admin edited weapons or execution shots with shotguns (or people with the frail quirk!)
-Piercing wounds make further wounds a bit easier to apply to give them a bit more power
-Hellguns now cost 2250 credits instead of 2000 to make them a bit harder for random crew to get
-Adds special bouncy L6 rounds for admins to use to bounce off anything and everything en-masse

Also as a minor note

Projectiles with no trajectory (meaning they were likely spawned in manually) now qdel themselves on bumping something, rather than runtiming helplessly

code/game/objects/structures/window.dm

@@ -27,7 +27,7 @@
 	var/breaksound = "shatter"
 	var/hitsound = 'sound/effects/Glasshit.ogg'
 	flags_ricochet = RICOCHET_HARD
-	ricochet_chance_mod = 0.4
+	receive_ricochet_chance_mod = 0.5
 
 
 /obj/structure/window/examine(mob/user)
@@ -371,7 +371,7 @@
 	state = RWINDOW_SECURE
 	glass_type = /obj/item/stack/sheet/rglass
 	rad_insulation = RAD_HEAVY_INSULATION
-	ricochet_chance_mod = 0.8
+	receive_ricochet_chance_mod = 1.1
 
 //this is shitcode but all of construction is shitcode and needs a refactor, it works for now
 //If you find this like 4 years later and construction still hasn't been refactored, I'm so sorry for this
@@ -683,7 +683,7 @@
 	explosion_block = 3
 	glass_type = /obj/item/stack/sheet/titaniumglass
 	glass_amount = 2
-	ricochet_chance_mod = 0.9
+	receive_ricochet_chance_mod = 1.2
 
 /obj/structure/window/shuttle/narsie_act()
 	add_atom_colour("#3C3434", FIXED_COLOUR_PRIORITY)