Checkbox label: check if we can strip out block-level elements

[sergei-maertens]

We have an existing bugs where the required asterisks can get pushed to the next line because the label of a checkbox is taken from some WYSWYG editor, leading to <p> element(s).

This is invalid markup - <label> is inline and may not contain block level elements. The WYSIWYG editors can apparently not be configured to not allow this either. Perhaps we can load the HTML and remove/replace the block level outer tags with linebreaks?