Moved redwood trees in forest biomes

[0Navis0]

It's just a suggestion I had already made for generating the redwood trees inside forest biomes intead of plain biomes. It would be more logic, and it looks better. I cleaned a bit the file since the forest generator was duplicated, so I reunified all the trees inside. I already tried it, everything seems to work fine.

[0Navis0]

It seems the pull request doesn't work well, it modifies the file and break the build. I tried to fix it, but it doesn't work. Anyway here is the file if you wanna check it, and not with the one proposed by the pull request. I built it and played with it, and it worked fine. https://github.com/Hypsellis/Natura/blob/1.12/src/main/java/com/progwml6/natura/world/worldgen/OverworldTreesGenerator.java