Add support for email, links starting with www and schemes in url autolinking

[asantos3]

Currently there isn't support for email and links starting with www. There's also no support for other schemes outside of http and https.

Invalid links

www.com
wwwgithub.com
github.com
@github.onet
foo@github

Valid links

foo@github.net
bar.ba@github.co.uk
support@github.com
www.github.com
ftp://www.github.com/rdfgi?rdfoghv
ftp://www.github.com
mailto://github.com

http://github.co.uk/
http://vnc.github.com:5800
http://github.com/foo.html?q=bar
http://github.com/dfiubuno?roin
https://www.github.com
https://github.com
ftp://www.github.com
ftp://github.com

[billglover]

This appears to be a limitation of the underlying marked package that is used by roaster.