Ref T4334. This aligns the lexer (but not the parser) with PHP 5.5.8. It also applies the patch on T3512. This has these positive effects:
- Fixes binary literals.
- Fixes empty heredoc.
- Corrects T_BINARY_CAST into T_STRING_CAST (consistent with 5.5.8).
- Removes T_UNICODE_CAST (not in 5.5.8).
- Recognizes keywords trait, __trait__, yield, insteadof, callable.
...these sideways effects:
- Slightly improves terminal heredocs (previously: parse error; now: bad parse).
...and these negative effects:
- Breaks the callable test, since callable is now recognized as a keyword but the parser doesn't yet support it.