Add parse_file() function

Small cleanups

* use ZVAL_STR_COPY
* Don't use cache slot for Node\Decl

Update README

Show return type hints

Decls now have 4 children and the last one is a name.

Don't dump linenos by default

For most purposes this is just noise.

In the test it looks like the lineno for AST_ARG_LIST is not being
computed correctly :/

Use ast\Node\Decl for declarations

Not including property declarations, as those do not use decl
layout.

Make test independent of ast_dump implementation

Tests shouldn't break when changing it...

Build on Travis

Fix test

Store the decl name as well if present

Update AST data

Update AST data

Fix compat with current master

ast/ast_arena are now pushed/poped with the lexical state.

More compact AST dump

Drop those {}

Fix compat with current master

Forgot to add TYPE_CALLABLE

Add flags

Use underscores for function names

Use persistent strings

Update README with some info

Add test

Remove stay whitespace in ast data generation

Use cache slots to update properties

Switch to object ast nodes (more compact)

Initial commit