Updated the lexer benchmarks.

These had to be updated for the API changes of Oga::XML::Lexer.
Basic benchmarks for the Parser class.
Truncate lines in parser errors.

The offending lines of code displayed in the error message are truncated to 80
characters. This should make reading the error messages less of a pain when
dealing with very long lines of HTML/XML.
Lex attributes with namespaces.

These are lexed as just the name instead of two separate tokens.