Add support for selector list

[Lyokovic]

Hi,

Here is the implementation of #15, thanks for your advice!
I was not sure if I should split the select function, it did not looked weird to me to leave it like that.

I quickly tested it with a simple selector and with a selector list and it seems to work as (I) expected.

[Lyokovic]

Hah, maybe running the tests could help... Back to work :p

[aantron]

Yes, thank you :)

I would recommend also adding new tests for the new functionality.

[aantron]

@Lyokovic, it turns out some of the test failures were caused by an upstream change. I've adjusted to that in master (see d51e1c3). After rebasing on master, there are still some failures, that look related to the new code, but the test results are much less noisy.

[Lyokovic]

I just pushed a fix of a quite obvious mistake. But there is still one more failure with my branch, I do not get what is wrong :/

I'll continue investigating and try to add some tests later.

[aantron]

No problem, take your time. And let me know if you would like any form of assistance :)

[aantron]

Closing this PR as stale.