Add option to enable/disable biome map rendering at low zoom levels

[Peregrine05]

Since Chunky is primarily rendering software, and is no longer intended to be used as mapping software, viewing the biome map is not particularly helpful in most cases. Instead, the block map may be more useful, even when zoomed out greatly.

[ConsueTerra]

Which version causes less lag?
I know on larger maps (like 4k by 4k) it takes a while for the full biome map to load, which I use to figure out which chunks to load.