zend_do_return -> zend_emit_final_return

Make lexer return AST nodes

Add functions for create str/long ast directly

Fix leaks

Must find a good way to handle constant expressions...

Implement declare()

__halt_compiler() without haling compiler

Partial NS port (semicolon, no errors)

Port constant declaration

Port use statement

Partial port of class declarations

Prepare zend_ast_decl for reuse with classes

Port trait uses

Port class const decl

Port property declarations

Port methods

The duplicated magic method checks are ugly

Support static closures

Handle function doc comments

Fix lexer/compiler interdependency

Use dedicated func_decl ast node

Functions need a bunch of extra info, that becomes inconvenient
to handle using the normal ast structure.

Port closures

Port closure use

Port __FUNCTION__ to AST

Preliminary function decl support

Problem: __FUNCTION__ etc don't work anymore, due to lexer/parser
interdependency.

Port parameter defs

Has one bug re \self

Rename params -> args