Only allows spawns of creatures above natural blocks; blocks are considered natural if their name satisfies any of the filters below:

• sand*
• gravel*
• dirtygravel*
• sludgygravel*
• muddygravel*
• soil*
• forestfloor*
• peat*
• rawclay*
• rock*
• crackedrock*
• regolith*
• ore-gem*
• ore-graded*
• ore-ungraded*

Might adversely affect dungeon spawns, but keeps helps keep drifters and other mobs out of your builds even if they are unlit.

Current issues:

• Temporal storms use different methods than worldgen or runtime spawn systems to create drifters, so this filtering doesn't work during storms.