Biome element needs a seperate PV range from Weirdness.

PV (peaks and valleys) are calculated from weirdness, but can be radically different. For example, I was getting a PV of around '-.98', but only had a weirdness of about '.1'.

Without the ability to set an actual PV range, it is impossible to get custom rivers to generate in river-like terrain. I have spent literal days trying to understand minecraft's biome system and one thing that was throwing me for a loop is why my river biomes would never spawn in river terrain, but would occasionally spawn on the side of mountains. This is why.