Remove the instance based on `query`

Property definitions

	# Remove the instance based on `query`
	fun remove(query: nullable QUERY): Bool is abstract

lib/popcorn/pop_repos.nit:195,2--196,52

	redef fun remove(query) do
		return collection.remove(query or else new JsonObject)
	end

lib/popcorn/pop_repos.nit:353,2--355,4