Group @testable imports at the bottom, per public/rules-swift's swiftformat. A
behavior-preserving import-ordering reformat across 252 files (mostly tests).
--trailingclosures was deliberately not adopted (cosmetic, and swiftformat flags
it as caution-worthy).
The eduni sections run with exact classified baselines. Fixes: 3.3.3
CDATA attribute-value normalization (literal whitespace to space before
reference decoding; char-ref whitespace survives; tokenized collapse on
SPACE only); production-68 lenient undeclared entities in content and
attribute values (validity finding, reference kept literal, nothing
fetched); errata E15 (references/comments/PIs/whitespace in EMPTY,
char-ref whitespace as data in element content, double-escape shape
included); errata E2 duplicate enumeration tokens; errata E14
declarations completed inside PE replacements (VC: Proper
Declaration/PE Nesting); NCName ID values; namespace declarations
subject to the every-attribute-declared rule. Reader validity machinery
split to EventReaderValidity for caps.
Closes#127
Add internal parameter entities (parsed, stored, and expanded within the
DTD, including bare %name; references that inject markup declarations,
bounded by depth and the expansion budget). Record external general
entities and the external subset identifier, and load them only through an
injected EntityResolver (a struct of closures). The default refusing
resolver fetches nothing, so XXE stays closed: an external entity fails as
undefined and the external subset is left unread. Internal declarations win
over the external subset.
Closes#29
