Expose PHP 7.1 ARRAY_SYNTAX flags

And fix the PHP 7.0 build again

Version 35: Forward/backward emulation of AST_CATCH format

Fix PHP 7.0 build

Add support for "iterable" type

Support nullable types

Represent these using a new AST_NULLABLE_TYPE virtual node.

Normalize to AST_STMT_LIST

Per @tpunt's suggestion.

Represent scalar types as AST_TYPE

Per @tpunt's suggestion.

Stip null elements from AST_STMT_LIST

Normalize ('\bar')() by removing leading backslash

Represent ?? as BINARY_OP

Deprecate version 15

Switching tests to version 30 where possible.

Deprecate version 10

Mark version 30 as current

No point in keeping it experimental if people already rely on the
format...

Fix PHP 7.0 build

Support PHP 7.1 class constant visibility

a) CLASS_CONST_DECL now uses modifier flags. For PHP < 7.1 we
emuate MODIFIER_PUBLIC here for consistency.
b) CONST_ELEM can now have a d

Support PHP 7.1 class constant visibility

a) CLASS_CONST_DECL now uses modifier flags. For PHP < 7.1 we
emuate MODIFIER_PUBLIC here for consistency.
b) CONST_ELEM can now have a docComment properts (in analog to the
property on PROP_ELEM).

show more ...

Avoid premature macro resolution / Fix OSX build

AST_STR(true) and AST_STR(false) were resolved to AST_STR(1) and
AST_STR(0), so go back to using a str_ prefix everywhere.

Mark version 20 as current

Add USE_* and MAGIC_* flag constants

This drops the effective dependency on tokenizer.

Also replace token numbers with %d as these are unstable.

Make $version argument required

[bc-break]

Move docComment to PROP_ELEM

Flatten nested STMT_LISTs

Some nodes like ECHO always get wrapped in STMT_LIST, resulting in
some weird syntax trees.

Use AST_VAR node for static var + catch var

For version 20. Previously this was a simple string with the
variable name.

Fix child names for virtual nodes

Use version 30 for named children