we basically added a mechanism to store the token stream during parsing
and exposed the entire parser stack on the tokenizer extension through
an opt in flag: token_get_all($src, TOKEN_PARSE).
this change allows easy future language enhancements regarding context
aware parsing & scanning without further maintance on the tokenizer
extension while solves known inconsistencies "parseless" tokenizer
extension has when it handles `__halt_compiler()` presence.