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/components.md

@@ -365,8 +365,14 @@ var Login = {
 	login: function() {/*...*/},
 	view: function() {
 		return m(".login", [
-			m("input[type=text]", {oninput: m.withAttr("value", this.setUsername.bind(this)), value: this.username}),
-			m("input[type=password]", {oninput: m.withAttr("value", this.setPassword.bind(this)), value: this.password}),
+			m("input[type=text]", {
+				oninput: function (e) { this.setUsername(e.target.value) },
+				value: this.username,
+			}),
+			m("input[type=password]", {
+				oninput: function (e) { this.setPassword(e.target.value) },
+				value: this.password,
+			}),
 			m("button", {disabled: !this.canSubmit(), onclick: this.login}, "Login"),
 		])
 	}
@@ -411,11 +417,11 @@ var Login = {
 	view: function() {
 		return m(".login", [
 			m("input[type=text]", {
-				oninput: m.withAttr("value", Auth.setUsername),
+				oninput: function (e) { Auth.setUsername(e.target.value) },
 				value: Auth.username
 			}),
 			m("input[type=password]", {
-				oninput: m.withAttr("value", Auth.setPassword),
+				oninput: function (e) { Auth.setPassword(e.target.value) },
 				value: Auth.password
 			}),
 			m("button", {