remove compat: `onEmbededElementDispose` in `embed:Element`

Removed backward compatibility for `onEmbededElementDispose`
callback (note the typo) in `embed:Element` controller.
Use `onEmbeddedElementDispose` instead.

(deprecated in 1.4.5 via GH-535)
remove compat: `password` property in `html:TextInput`

Removed the `password` config property of `html:TextInput`.
Use `attribute.type = password` instead.

(deprecated in 1.4.6 via GH-551)
remove compat: non-standard dataset keys in utils.Html

Removed backward compatibility when the user was using
non-standard dataset keys in `aria.utils.Html` methods.

(deprecated in 1.4.7 via GH-499)
remove compat: `cssClass` in sections and repeaters

Removed backward compat for `cssClass` property in sections
and repeaters. Please use `attributes.classList` instead.

(deprecated in 1.5.2 via GH-1086)
remove compat: `escape` modifier

Removed the `escape` modifier available in the templates.
Please use `escapeforhtml` modifier instead.

(deprecated in 1.5.3 via GH-1099)
remove compat: unused jsunit classes

Removed some `aria.jsunit.*` classes that are no longer supported.

(deprecated in 1.5.3 via GH-1104)
remove compat: `onpopstate` event from utils.History

Removed backward compatibility for `onpopstate` event raised by
aria.utils.History.
Use `popstate` event instead.

(deprecated in 1.6.3 via GH-1124)
remove compat: boolean param for sync requests in submitJsonRequest

Removed backward compatibility in
`aria.templates.ModuleCtrl.submitJsonRequest` method:

Since 1.6.2 the method accepted boolean param (at 4th position)
which, when set to `false`, made the request synchronous.

This was deprecated in 1.6.7 in favor of passing an object with
options, which is more versatile and apart from setting `async` flag,
can be used to override timeout and headers.

In other words, if you used

    `submitJsonRequest(.., .., .., false)`

you should use instead:

    `submitJsonRequest(.., .., .., {async: false})`

Note that synchronous requests will freeze the UI of the browser
and should not be used unless you have a valid use case for them.

(deprecated in 1.6.7 via GH-1316)