Make fumaroles regenerate or make them immune to Ripple

[Baark0]

Fumarols are the main miasma producers when a shadow rift is active, which is important because Ripple needs to eat miasma to grow longer. The problem is, it is very common for Ripple to walk into a fumarole, permanently destroying a source of miasma. Either of the changes suggested in the title would negate this, though I'd prefer the first change since worlds before the latter change would still be screwed if all the fumaroles had already been destroyed.