libxml-rs 0.1.0-alpha.8

Phase 7: C14N, XML Reader/Writer, Regex, Automata, Debug. Native-Rust forensic reimplementation of libxml2+libxslt with C ABI drop-in replacement. 957 tests passing, C14N (inclusive+exclusive), XML Reader (full tree+stream+attribute traversal), XML Writer (document+element+attribute+PI+comment), Regex (44 tests: NFA, anchors, char classes, quantifiers, determinism, incremental execution), Automata (state machine infrastructure), Debug (tree dump, ls, attr dump), all prior surfaces.