Swift support, improved styling support

[Legoless]

This pull request adds 3 features:

• Swift API enhanced compatibility with Nullability modifiers
• Ability to style buttons added to the alert view by providing a custom block
• Ability to choose color for button separator

[kubatruhlar]

Nice job, would you mind to remove extra double spaces (line 135 etc.) and space behind the * (like line 94, 24 etc.)?

[Legoless]

Something like this? :)

[kubatruhlar]

I mean UIButton* btn should be UIButton *btn in .h and in .m as well. Otherwise its good 👍

[Legoless]

I'm not sure what you mean, they are the same on both sides?

[kubatruhlar]

It's just a style preference, the space doesn't mean anything in this case, but keep the style of this code please.

[Legoless]

Of course, I'm keeping style the same, but maybe just Xcode formats it in a way I cannot see what you want changed. Can you be more specific?

[kubatruhlar]

Don't you see space after asterix? Everywhere you put UIButton* btn, you are supposed to put the space before not after the asterix.

[Legoless]

Oh yeah, that's what you mean, sorry :) Fixed now, I hope.