Normalize line endings in the Reader as the spec requires, which was not
done before:
- CR and CRLF fold to a single line feed (XML 1.0), so every downstream
scan sees line feeds only.
- When the declaration names version 1.1, NEL (U+0085) and LINE SEPARATOR
(U+2028), and a CR followed by NEL, also fold to a line feed; in 1.0
those characters are preserved as data.
The XML 1.1 name-character productions are identical to XML 1.0 Fifth
Edition, which the character classifier already implements, so names need
no change. The 1.1 character range (C0 controls permitted only as
references) is not yet enforced.
Closes#96
Parse the XML declaration's pseudo-attributes instead of skipping the
<?xml?> processing instruction:
- version, encoding, and standalone are surfaced on a new XMLDeclaration,
returned from parseWithDocumentType and via PureXML.xmlDeclaration(_:).
- The pseudo-attributes are validated: fixed order (version, encoding,
standalone), known names only, and standalone must be yes or no. A
malformed declaration is rejected.
- The declared version is now readable, a prerequisite for XML 1.1.
parseWithDocumentType returns a ParsedDocument struct (node,
documentType, declaration) rather than a 2-tuple; the member names are
unchanged so existing call sites are unaffected.
Closes#95
