Expr stmts go through ast

Make statement asty

Port goto label

Make unticked_statement an ast node (usually NULL)

Port goto

Port break/continue

Port throw

Port echo

Port return statement

Refactor class name resolution as well

Shared name production for const / fn name

Some refactoring of fn/const resolution

Drop addition of weird \ prefix for FQ consts

Also fixes a resolution bug

Rename ZEND_CONST to ZEND_AST_ZVAL

Remove obseleted grammar productions

Reuse expr for static_scalar

Handle ::class in const expr via ast as well

Compile const refs to CONST

Compile class const refs to CONST zval

Remove static_scalar_base

Handle trait __CLASS__ in parser

Bring static scalar arrays in line

Bring static scalar AST more in line with normal AST

Const eval unary pm (as previously)

Move T_STRING_VARNAME handling