CoralVM-PHP: Adding open_manager method to TreeManager and making its constructor public
CoralVM-PHP: Adding context_identifier method to TokenLayer
CoralVM-PHP: Preparing basic implementation of AST building managers from global up to function body

Excluding classes and other advanced structures for now. The AST builder now stops at function body block level and dumps the separated expressions. Tokenizer itself is unable to correctly do this without lookahead with real tokens.