This change adds the ability to instantiate Message objects from
multipart MIME email strings.

Most of the functionality was already there; there was even a commented
out stub that outlined the start of what was required. However, I think
because the supporting functionality was lacking in laminas-mime, it was
not implemented.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

This change adds assertions for the content of the various parts of
message. The intention is to be able to check deeper into a multipart
message to confirm that it is as expected. As the underlying test data
contains a PDF file, it adds the smalot/pdfparser to simplify working
with PDF files.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

From my understanding of the various specs, primarily RFC 1341, the
existing functionality for setting message headers was wrong. Given
that, I've made this change, which should bring it into line with the
spec, corrects issues with the existing tests, and sets one existing
test as skipped (for the time being).

Firstly, it removes the functionality that sets headers on the main
message from message sub-parts. Secondly, equally as importantly, it
sets the required headers, along with their defaults, based on the
message's composition. I won't get into detail here, as it's documented
in the code and in the updates to the documentation.

Finally, the change also cleans up some of the existing functionality as
well, setting return types, as they're supported in the package's
allowed PHP versions.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

This commit updates the relevant sections of the documentation to
reflect the changes in how mime messages are created. It also does a
little bit of cleaning up of the documentation as well.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

I think that I inadvertantly checked in a composer.lock file which
referenced a local fork of laminas-mime that I was working on while
patching the library. This change reverts that.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

After feedback from @MWOP, this change simplifies test data for testing
the HTML part of an email. It removes SendGrid details, to ensure that
the tests don't favour any given provider.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

This change adds three custom RecursiveIterator classes with the aim of
simplifying working with message parts.

- PartsIterator simplifies iterating over a recursive list of parts, as
  multipart mime email parts can themselves contain parts.
- MessagePartFilterIterator is designed to use PartsIterator to filter
  out parts that are not the contents of a message, such as the plain
  text or HTML body.
- AttachmentPartFilterIterator is designed to use PartsIterator to
  filter out parts that are not message attachments.

Together, these iterators will help provide functionality for quickly
retrieving a message's content and attachments, without leaving it to
the user.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

You can iterate over all of the message parts in the calling code and
extract the plain text and HTML body, as well as the attachments.
However, I thought that this would be something that people would do
regularly; so much so such that adding utility functions for doing so
might be a great productivity win for the package.

The documentation's been updated to reflect these additions so that
they're as visible as possible, and readily discoverable.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>