add tnt compatibility

[fluxionary]

1. drop the item in the anvil (currently it is just lost)
2. remove the entity (currently it can persist without the anvil)

[SmallJoker]

LGTM. Will merge in a few days unless there are objections.

[OgelGames]

Looks like this is missing code to preserve the anvil's shared state, as is done when digging the anvil:

anvil/init.lua

Lines 238 to 245 in cafef4e

	preserve_metadata = function(pos, oldnode, oldmeta, drops)
	if next(drops) and tonumber(oldmeta.shared) == 1 then
	local meta = drops[next(drops)]:get_meta()
	meta:set_int("shared", 1)
	meta:set_string("description", S("Shared anvil"))
	end
	return drops
	end,