Emailprint button templatization

[rica-carv]

Motivation and Context

Suggested option to fully allow templatization of buttons, either bootstrap output or not. Buttons can be rendered as A tags or BUTTON tags, and the HTML hardcoded inside the PHP makes the customization a lot harder than with templates. Templates can even allow the templatization at theme level, much easier without rewriting the whole PHP code to have a custom button, like for instance, with text besides icon....
If approved, this can also be the starting point of allowing templatization of e107 buttons, etc....

Even better, this code is only currently used in news, but it can be used also in forum, etc., to allow a standardization of layouts sitewide....
Just my 2 cents...

Description

Changed hardcoded HTML to a new template, and leave old code for legacy purposes commented.

How Has This Been Tested?

Tested in last github e107 code

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist

• My code adheres to the e107 code style standard.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests pass.

[codeclimate]

Code Climate has analyzed commit ce99d9e and detected 4 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Bug Risk	4

The test coverage on the diff in this pull request is 85.1% (80% is the threshold).

This pull request will bring the total coverage in the repository to 39.0%.

View more on Code Climate.