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@example.com firstname.lastname@example.com email@subdomain.example.com firstname+lastname@example.com 1234567890@example.com email@example-one.com _______@example.com email@example.name email@example.museum email@example.co.jp firstname-lastname@example.com

[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:

gâteau@cake.com

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:

test@xn--bcher-kva.com

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 
JosễSilva@google.com
FoO@BaR.CoM
john@192.168.10.100
gómez@junk.br
Abc.123@example.com.
user+mailbox/department=shipping@example.com
用户@例子.广告
उपयोगकर्ता@उदाहरण.कॉम
юзер@екзампл.ком
θσερ@εχαμπλε.ψομ
Dörte@Sörensen.example.com
аджай@экзампл.рус
test@xn--bcher-kva.com
gâteau@cake.com
test@莎士比亚.org
email@example.com
firstname.lastname@example.com
email@subdomain.example.com
firstname+lastname@example.com
1234567890@example.com
email@example-one.com
_______@example.com
email@example.name
email@example.museum
email@example.co.jp
firstname-lastname@example.com

[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.