Deservicify core (#2458)

* De-servicify router (mostly)

Still uses the redraw service, but it no longer has an intermediate
service of its own.

Also, did a *lot* of test deduplication in this. About 30-40% of the
router service tests were already tested on the main router API instance
itself.

Bundle size decreased from 9560 to 9548 bytes min+gzip.

* Merge `m.mount` + `m.redraw`, update router

Simplifies the router and redraw mechanism, and makes it much easier to
keep predictable.

Bundle size down to 9433 bytes min+gzip, docs updated accordingly.

* Make `mithril/render` just return the `m.render` function directly.

* Deservicify `m.render`, revise `m.route`

- You now have to use `mithril/render/render` directly if you want an
  implicit redraw function. (This will likely be going away in v3.)
- Revise `m.route` to only `key` components

* Add `redraw` to `m.render`, deservicify requests

* Test error logging

* Update docs + changelog [skip ci]

test-utils/throttleMock.js

@@ -3,17 +3,8 @@
 module.exports = function() {
 	var queue = []
 	return {
-		throttle: function(fn) {
-			var pending = false
-			return function() {
-				if (!pending) {
-					queue.push(function(){
-						pending = false
-						fn()
-					})
-					pending = true
-				}
-			}
+		schedule: function(fn) {
+			queue.push(fn)
 		},
 		fire: function() {
 			var tasks = queue