Burnable walls are inconsistent with original

[lethal-guitar]

For example, in level M5, shooting the first wooden wall makes the whole wall burn up, whereas only part of it burns in the original.

The root cause is the lack of limitations in RigelEngine. The original restricts effect sprites to 18 at a time, which causes some of the fire effects to not spawn, leaving parts of the wall intact. To replicate this in Rigel, we have to replicate the limitation.