Updated plantlife

- Added `if` statements to avoid populating areas when lag is too high

mods/plantlife_modpack/nature_classic/config.lua

@@ -1,6 +1,6 @@
 -- Set on which distance from water can the tree still grow.
 -- Grows anywhere if set to -1.
-DISTANCE_FROM_WATER = 20
+nature.distance_from_water = 20
 
 -- Minimum light level needed to grow. Default is 8, which means daylight.
-MINIMUM_GROWTH_LIGHT = 8
+nature.minimum_growth_light = 8