API: Change getAttributesHTML to AttributesHTML

Currently it is impossible to use `$AttributesHTML('class')` in your template to output all attributes except 'class'. Instead you are forced to use `$getAttributesHTML('class')` this seems inconsistent. So I have replaced `getAttributesHTML` with `AttributesHTML`.

This is because when using `__get()` the method is always called with no parameters which causes `$AttributesHTML('class')` to currently not work.

Also sorry for the duplicate PR #2481