add php stubs for IDE support

[andheiberg]

For IDE's to pickup the classes you're generating with C you need to write stub files.

Here you go for the current interface. Doesn't seem like there's an automatic way to generate these :(

Side note: I was looking into the involved in adding proper AST classes instead of returning as array. It's fairly involved :( this is a script that does it for Ruby. But then on top of that we would need to make something that creates stub files for those automatically. I don't know if this is worth it, but it sure would be nice. Might just do a conversion from array to AST in PHP for now.