[WIP] Detect functions declared in the same file

[vudaltsov]

Fixes #179

• [x] make test fail
• [ ] fix the issue

[vudaltsov]

I think, I found the problem.

https://github.com/nikic/PHP-Parser/blob/master/doc/component/Name_resolution.markdown

Unqualified function and constant names inside a namespace cannot be statically resolved. Inside a namespace Foo, a call to strlen() may either refer to the namespaced \Foo\strlen(), or the global \strlen(). Because PHP-Parser does not have the necessary context to decide this, such names are left unresolved. Additionally a namespacedName attribute is added to the name node.