* Rework Lavaland tunnel themes.
* Fix deeprock mob density; ensure 1 vetus/bubblegum
* goddamnit
* bring spawn odds closer in line to head, fix tendril collapse range
* Move define to global dir
* don't need initial here
* define magic number properly
* make type of var clear
* CHECK_TICK during procgen
* less tendril cities, no tendrils in oasis centers
* revert no_lava helpers for now
* add NO_LAVA_GEN flag check back to safe_replace
* add blackbox feedback for themes