Don't unload locations where something is growing
Don't unload locations where something is growing

* don't unload locations with items that have an `onGrow` timer; this
  is pretty crude, but works to keep locations loaded until all ice
  nubbins, barnacles, jellisacs and peat bogs have grown back

Fixes https://trello.com/c/0udEozF3

Whizy/eleven-server,Whizy/eleven-server,KaiyonAlatar/eleven-server,ElevenGiants/eleven-server,KaiyonAlatar/eleven-server,KaiyonAlatar/eleven-server,ElevenGiants/eleven-server,Whizy/eleven-server,ElevenGiants/eleven-server,yelworc/eleven-server,yelworc/eleven-server