Remove the edge from base

Property definitions

neo4j $ Neo4jClient :: delete_edge
	# Remove the edge from base
	fun delete_edge(edge: NeoEdge): Bool do
		if not edge.is_linked then return false
		var url = edge.url.to_s
		delete(url)
		local_edges[url] = null
		edge.url = null
		return true
	end
lib/neo4j/neo4j.nit:200,2--208,4