#30 Support OAuth

[lwc]

Following this discussion, here's an official request.

Services like Gmail no longer allow third party usage without either OAuth or App Passwords. While the latter can be done without involving Blat involved, it's more cumbersome.

[Chip]

When last I checked, OAuth requires HTTPS support, which brings in a whole other area of problems. Adding https support necessitates openssl for SSL/TLS support, security certificates, and more. Plus, this moves the needle away from providing SMTP services to only supporting HTML services where Google can more easily inject advertisements and tracking (etc.). HTML is not conducive for simple e-mail transport.

[lwc]

See related feature request about SSL.