Add replaceNode switch (#141)

* Add replaceNode switch

* Add test for replaceNode()

* Update TS definitions

tests/lib/switches.js

@@ -0,0 +1,24 @@
+var tape = require("tape")
+var switches = require("../../lib/switches")
+var noop = require("../../lib/util/noop")
+
+tape("test replaceNode switch", function(t) {
+  var replaceNode = switches.replaceNode
+
+  var doc = document.implementation.createHTMLDocument()
+
+  var container = doc.createElement("div")
+  container.innerHTML = "<p>Original Text</p>"
+  doc.body.appendChild(container)
+
+  var p = doc.createElement("p")
+  p.innerHTML = "New Text"
+
+  replaceNode.bind({
+    onSwitch: noop
+  })(doc.querySelector("p"), p)
+
+  t.equals(doc.querySelector("div").innerHTML, "<p>New Text</p>", "Elements correctly switched")
+
+  t.end()
+})