Fix magic methods called directly on dataobject

[hostep]

Hi!

Been using this phpstan extension for a couple of days now, it's being very much appreciated!

Today I noticed a small problem, in that I was instantiating a DataObject class and called some setters on it. And phpstan was complaining about calling undefined methods on it, even though this extension was installed which was supposed to fix this.

The problem was, that this extension only checked on subclasses of DataObject and not on instances of DataObject itself.
This PR fixes this.

I also took the liberty to ignore the /vendor/ directory in the .gitignore file which was missing.

Awesome work with those captainhook scripts btw! First time I've been using them in practice even though I told myself to look into those after seeing your very nice talk on MM19NL 😉

[shochdoerfer]

Thanks for your contribution! Good catch :)

[shochdoerfer]

I usually have set-up a global .gitignore file, thus I tend to forget that other developers don't have that. Thanks for that minor improvement.

[hostep]

Thanks for merging so quickly!