Allow a const/variable's value to be used as a type

[nickyr]

For example,

class A {
    const CLASS = '\My\Namespace\Class';

    /**
     * @return self::CLASS
     */
    public function foo() 
    {
        // ...
    }
}

[nickyr]

Would be helpful for #16 also

[nickyr]

For a real world example, see https://github.com/vimeo/omnipay-vindicia/blob/5f97e6eb9dfdae8e3cc888e32edd584de27a5846/src/Message/AbstractHOARequest.php#L30-L36, where reflection is being used to fake double inheritance.

[muglug]

Psalm has @return class-string now FWIW

[nickyr]

Nice! I see that's documented for @param here: https://github.com/vimeo/psalm/blob/master/docs/supported_annotations.md#class-constants

is it documented for @return?

[muglug]

Ah, the docs weren't clear – I've improved them.

[muglug]

Not going to support this beyond what's already supported with enums