PHP Mail Helper Refactor

[thinkingserious]

Issue Summary

An interface to easily interact with the mail/send endpoint of the SendGrid v3 Web API.

The specification for this project is here and the discussion around this specification can be found here.

Acceptance Criteria

All of the use cases defined here are implemented and all corresponding tests are passing.

[COil]

Hi the rewrite is very welcome. When looking at this php class sendgrid/php-http-client/lib/SendGrid/Client.php for example it looks like PH4 code, no access modifier declared, properties declared dynamically, etc...

[thinkingserious]

Please see this comment regarding making parameters optional.

[thinkingserious]

Hello Everyone!

@COil @zanderwar @caseyw @izhukovich @Tzafra @senorgeno @vitya1 @Braunson @cbschuld @paoga87 @Taluu @mazanax @ninsuo @ianh2 @WadeShuler @jaimehing @KnightAR

Development on the SendGrid PHP Mail Helper Refactor is underway on this branch. The example in sendmail.php is currently working on that branch.

The next step over the next few days is to implement the Kitchen Sink example and then implement the corresponding tests. I will then look at the issues that are linked (e.g. #321). Then, I should be able to release v7.0.0 shortly afterwards to Packagist.

Your feedback during this home stretch is greatly appreciated! I want to make sure we have a solid v7.0.0 base from which to iterate on.

Thanks!

With Best Regards,

Elmer