and improve lag management
minetest.conf settings added:
biome_lib_dtime_limit:
Maximum lag allowed, in seconds. Default 0.5s. Larger values allow for
more lag, but make map updates run a bit faster.
biome_lib_queue_run_ratio:
If positive, this is the approximate number of globalstep ticks to skip
between map updates. If negative, it becomes the positive number of map
updates to run per globalstep tick before lag is checked. No minimum
value, maximum +100. Default: -100 (that is, 100 updates per globalstep
tick, with none intentionally skipped). Use positive numbers for slow
machines or biome_lib-using mods that tend to cause lag, and negative
values for fast machines and mods.