Tokens transformators

Proof of concept about transforming tokens (resolve #531).

- [X] add mechanism for support tokens transformation
- [X] add `CT_ARRAY_TYPEHINT` for `T_ARRAY` used as typehint (fix #542)
- [X] create `CT_CURLY_CLOSE` for `T_CURLY_OPEN`
- [X] create `CT_DOLLAR_CLOSE_CURLY_BRACES` for `T_DOLLAR_OPEN_CURLY_BRACES`

If merged then I'll create a Transformators for :
* create tokens for braces in syntax: `$this->{$foo}`
I agree. Using a static property is probably not worth it here. OPCache should already be able to optimize the array (at least partially, and it may become better in future versions)

And a static property means the memory cannot be reclaimed until the end of the process.