Issue #167 - valid email-addresses with IDNs do not validate

[sprak3000]

What?

• Use a regexp to allow international characters throughout e-mail address. Using a regexp avoids the need to install / use any special extensions, e.g., idn_to_ascii() from the php-intl extension.
• Add two new entries to the valid e-mail data provider -- one for an IDN character in the domain portion of the e-mail address, one for an IDN character username portion.

Checklist

• Added unit test for added/fixed code
• Updated the documentation
• Scrutinizer code coverage is 100%
• Scrutinizer code quality is as high as possible

Linked issue

#167

[RobQuistNL]

You might want to add some more emailadresses to check, as well as some (much more) invalid e-mail adresses. Since this is quite a big change, you know :)

[peter279k]

Like @RobQuistNL says, this validation approach is the big change because the original approach uses the native filter function to validate e-mail address. And the new change use the regular expression.

I agree with @RobQuistNL, and It should add more tests to prove the regular expression can validate e-mail address currently 👍.