Frostwork 0.2.0

Backward-incompatible changes

• A document with no BOM, label or declaration is no longer assumed to be UTF-8: it is UTF-8 if it is
  valid UTF-8, and otherwise its encoding is autodetected, as Firefox does. Pass the response URL as
  url to extract, extract_grouped, detect_encoding, Plan, Page.extract and
  frostwork.encoding.autodetect_encoding so that its top-level domain informs the guess (.jp
  favours Shift_JIS, .ru windows-1251, …), as it does in browsers.

• In Rust, extract, extract_grouped, detect_encoding, Plan::extract,
  Page::extract_with_encoding and CompiledPage::extract_with_encoding take the response URL as a new
  url: Option<&str> argument after the encoding. Pass None when there is no URL.

• bgsound, embed, keygen, source, track and wbr are now void elements, matching libxml2
  2.15, the oracle Frostwork now targets. Markup after one of them is no longer its child, e.g.
  <div><source><span>x</span></div> matches div > span instead of source span.

Python API and tooling

• frostwork.encoding exposes each step of detect_encoding() (bom_encoding(),
  declared_encoding(), autodetect_encoding()), plus decode(), which decodes as browsers do where
  Python's codecs differ (e.g. euc_jp), and codec_name(), which gives the Python codec name of any
  label resolve_label() resolves. It lets a library that keeps its own encoding API, such as w3lib,
  give browser answers. Importing it registers Python codecs for x-user-defined and replacement.
  See PYTHON.md.

• frostwork.navigation() reads the base URL and meta refresh of a document as a browser does, and
  Page.extract_with_navigation() reads them in the same pass as the fields; in Rust, navigation()
  and Plan::extract_with_navigation(). See
  PYTHON.md.

• The refusal reason of a selector with an unsupported pseudo-class or pseudo-element now names it,
  e.g. pseudo-class `:hover` is unsupported, also when it sits next to a supported one
  (li:nth-child(2):hover).

• frostwork.page.detect_encoding() and frostwork.page.resolve_label() are deprecated; use
  frostwork.detect_encoding() and frostwork.resolve_label().

Correctness

• The <meta> prescan skips other tags together with their attributes, as browsers do, so a
  <meta charset> inside an attribute value (<img alt="<meta charset=big5>">) no longer declares the
  encoding.

• A selector deferred on an ancestor (:has(), :contains(), a reverse position such as :last-child
  or [last()]) followed by a descendant step that the ancestor itself could match, such as * or its
  own tag, no longer returns that ancestor, e.g. li:last-child * returned the <li> as well as its
  descendants, and //li[last()]//*/@class its class.