Feature/improve email extract

[klaxon1]

To resolve #365
Used email regex from https://www.regular-expressions.info/email.html
Added some basic tests.
The following email address are valid:
[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]

[edent]

Does this work with I18n domain names?

For example test@莎士比亚.org

(from https://shkspr.mobi/blog/2016/09/why-cant-you-send-email-to-a-chinese-address/)

[GCHQ77703]

It does not appear to. Nor does it appear to work with any non-latin characters anywhere in the email address. E.g:

gâ[email protected]

This is actually allowed though, according to RFC 5322, which specifically stipulates only latin characters in email addresses. Non-latin characters are usually converted into something that looks like:

[email protected]

Behind the scenes of whatever client you are using. Despite such characters not being allowed in some MTAs, might still be reasonable to support them ourselves as they are ubiquitous.

[klaxon1]

good point all, i didnt consider those cases. lets leave this pull request open and i'll make some additional commits.

[klaxon1]

so, I've learnt this week that email addresses are more complicated then i originally thought.
Hopefully this updated regex (from https://www.regextester.com/98066) seems to match 99% of valid email addresses.
The following email address are all extracted successfully:

伊昭傑@郵件.商務
म@मोहन.ईन्फो
юзер@екзампл.ком
θσερ@εχαμπλε.ψομ 
JosễSilvễ@googlễ.com
JosễSilvễ@google.com 
Josễ[email protected]
[email protected]
[email protected]
gó[email protected]
[email protected].
user+mailbox/[email protected]
用户@例子.广告
उपयोगकर्ता@उदाहरण.कॉम
юзер@екзампл.ком
θσερ@εχαμπλε.ψομ
Dörte@Sörensen.example.com
аджай@экзампл.рус
[email protected]
gâ[email protected]
test@莎士比亚.org
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]

[n1474335]

Excellent, thanks very much for this. I haven't updated the built in email regex in the 'Regular Expression' operation as I feel this version should be a bit more quick and dirty. It's useful to have a fairly accurate one for 'Extract email addresses' though.