Add NS error checks

Those can probably be implemented in a better way now...

Discard NS doc comments

Fix namespace\, maybe

Port top level stmt

Problem: namespace\foo no longer works :/

Partial NS port (semicolon, no errors)

Port constant declaration

Port function/const use

Port use statement

Port __TRAIT__ and __CLASS__ to AST

Mostly finish class declarations (~50 failing tests)

Partial port of class declarations

Prepare zend_ast_decl for reuse with classes

Throw \self etc error

Could only enable this now that everything uses the new format

Fix class name resolution in traits

Improve class name handling

Port trait uses

Handle class const doc comment

Property doc comments not yet handled

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