Chain Reaction

Provides a workaround to https://gitlab.com/foundrynet/foundryvtt/-/issues/6417 , allowing rolls such as 1d20x10x20 to explode continually on both numbers.

Multiple xo modifiers are handled seperately - e.g. 1d20xo10xo20 will explode once on a 10 AND once on a 20, if both are rolled.

Unlikely to come to core, as this is a somewhat hacky workaround and getting this behaviour in core in a sensible way would require more significant retooling of how dice modifiers work which is probably not worth it for how niche this issue is (and because any system needing this can implement their own modifier to do this better).