Somewhat fix the sit command

NPC's now sit on little entity arrows... that sometimes bug themselves
for no good reason and kind of mess things up. but at least it sits
temporarily. Also it stands wrong. sometimes takes the stand command
twice and a teleport to get it going.
Don't require NPCs be spawned for cuboid.list_npcs

Yay one-line commits
Don't show NPCs in list_entities

Entities != NPCs for our purposes.
Make list.contains take a list

basically a list.contains_all
Make list_npcs work properly

work with despawned NPCs
Add Denizen debug -o

Toggle OVERRIDE of 'debug: false' mode
Quiet the proximity trigger

Who cares if the move trigger is missing? Shut up!
Listen to dScript.yaml_key errors

Try to identify errors
Add a glitchy entity rotation property

Is far from perfect!
handle BigDecimal errors

BigDecimal is pretty poor at math too, try both BigDecimal and Double
before giving up.
Add tag list.filter

Incredible list-handling power!
Add dLocation.skull_skin tag/mech

Skull control!
Merge pull request #869 from mcmonkey4eva/master

Pull request for NPCs and numbers
Merge pull request #868 from Morphan1/master

Inventory-related fixes