Support `@psalm-internal`

[weirdan]

BCC supports @internal docblock tag that can be used to limit access to the top-level namespace (at least, that's how Psalm interprets it).

Psalm also supports @psalm-internal tag that allows you to grant access in a more modular fashion (you can reference sub-namespaces, classes, and even individual methods and functions), but BCC ignores that tag.

[Ocramius]

Analysis of various symbols is context-less, so a @psalm-internal \Some\Namespace would be equivalent to @internal for this tool: is that sufficient?

[weirdan]

I think that would be sufficient, it's better than nothing, for sure.