Remove m.prop + m.withAttr (#2317)

* Remove `m.prop` + `m.withAttr`

- For many uses, `m.withAttr` is *more* verbose than just directly using
  an event handler
- If you're using it with a bound callback, you're literally wasting a
  single character in the human readable version (and you're *saving*
  them in the minified output).
- It sometimes obscures your intent, if overused.
- Functions are easier to compress than `m.withAttr`, resulting in
  slightly smaller bundles.
- `m.withAttr` is overused anyways.
- `m.prop` is basically useless without `m.withAttr`, and the API
  doesn't have the same benefits it had with 0.2.x.

* Update changelog

docs/stream.md

@@ -306,7 +306,7 @@ In the example above, the `users` stream is populated with the response data whe
 
 #### Bidirectional bindings
 
-Streams can also be populated from other higher order functions, such as [`m.withAttr`](withAttr.md)
+Streams can also be populated from event callbacks and similar.
 
 ```javascript
 // a stream
@@ -314,7 +314,7 @@ var user = stream("")
 
 // a bi-directional binding to the stream
 m("input", {
-	oninput: m.withAttr("value", user),
+	oninput: function (e) { user(e.target.value) },
 	value: user()
 })
 ```