Address hoaproject/Central#81.

Define minimal supported version of PHP needed into composer.json

Address hoaproject/Central#70.

`hoa/socket` is now mandatory and `hoa/file` is upgraded to `~1.0` in
dev-dependencies.

SMTPS uses the port number 465. It avoids the use of `STARTTLS` and
forces TLS directly. So if w...

The core is being splitted into several libraries. `Hoa\Exception` is
one of them.

Line reading:
* The `ifNot` method now returns a line as a string or many lines as
an arra...

In the case the server does not support `STARTTLS`, we always re-sent a
new `EHLO`. While this o...

In RFC2392, Section 2, we must not miss this part:

> … and enclosing the remaining parts with a...

Encoders have a different behavior when encoding a content or a header.
See RFC2047 Sections 4 a...

Please, see RFC4648.

Please, see RFC2111. This allows to “embed” content, i.e. attach a
content and then reference it...

See RFC2111. It manages the `content-id` header.

We follow Praspel standards with `\result`.

We apply the same computing to `to`, just like we do for `cc` and `bcc`.

Before it was defined when calling `_getContent` if not defined. So it
defined only once and, mo...

For instance, if the stream is a string buffer, `Hoa\Mime` will throw an
exception because the s...