[FEATURE] Backend module button to delete all mails and answers on current page

[cweiske]

Located in Backend > Mails > Function check

Screenshot: http://fotos.cweiske.de/screenshots/2018/2018-07-03%20powermail%20delete%20all.png

[einpraegsam]

First of all: Thx for your work, I like your change and think we can merge such a feature. I also like the anchor for the email form.

But I would like to discuss with you:

1. Isn't it a bit too complicated programed with a checkbox "keepall" and "reallydelete"? If this is just a security feature to prevent clicks by accident, I would simply add a JavaScript inline confirm(). This will keep the php code shorter then now I think.
2. The action in backend is called "function check". But your new feature is not a function check. But I also have no idea where to place such a feature. If we would move this action to a different place, we could use an action method alone for this feature (at the moment one actions does two different things - what is not so nice in my eyes). Any ideas for a better place?

In addtion - please respect PSR-2 and a good coding style:

• if else should be ifelse in Classes/Controller/ModuleController.php:190
• Please compare in PHP only type secure === is always better then == (same line and 3 lines above)

[einpraegsam]

Any feedback? Otherwise I'm forced to close this PR.

[cweiske]

I'm just back from vacation and will need some time to look into it. -- Regards/Mit freundlichen Grüßen Christian Weiske