replace call_user_func() call

Permit use with type-assert v4

Fix some hhvm 4.34 BC breaks (#11)

hhvm 4.34 compatibility

support new versions of HHVM

- static local variables were removed from the Hack language recently
- implicit `(string)` cast on objects is no longer allowed

Ensure compatibility with hhvm 4.1

- usage of `func_get_args` has been removed
- Mocking `isDestructor` is no longer supported

Remove decl declaration

Update dependencies and bump hhvm to 3.30 (#6)

3 default boolean value (#4)

* Fix default boolean values (#3)

* Clarifying change (#3)

Fix typo

Update readme