Vgstation13: No upper limit on rigged power cell explosion

[kernikov]

Description of issue

Blobs eating power cells causes a rigged power cell explosion.
`/obj/item/weapon/cell/proc/explode()
var/turf/T = get_turf(src.loc)
/*

• 1000-cell explosion(T, -1, 0, 1, 1)
• 2500-cell explosion(T, -1, 0, 1, 1)
• 10000-cell explosion(T, -1, 1, 3, 3)
• 15000-cell explosion(T, -1, 2, 4, 4)
• */
  if (charge==0)
  return
  var/devastation_range = -1 //round(charge/11000)
  var/heavy_impact_range = round(sqrt(charge)/60)
  var/light_impact_range = round(sqrt(charge)/30)
  var/flash_range = light_impact_range`

This is fine and dandy but there is no upper cap.
If, for whatever reason, like bus or a really really stupid trial admin, a extremely large capacity power cell is bussed in and is consumed, you get a, impossibly large explosion that can cripple the server.

Difference between expected and actual behavior

Expected: A very large explosion
Actual: An exploded server

[bugfix]

[d3athrow]

lol