Revert template changes from Mustache back to Smarty

[Groruk]

Description

Sadly changes to the template engine/templates have been pushed back to a point after the release of version 1.7.0
This PR reverts the already made changes back to smarty.
The last big changes before 1.7.0 is being released are detailed in the 1.7.0 Project.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.