Fix add_class_to_el templatetag to work with lists for classes

added part::frontend type::bug labels

added 8 commits

• d52396d0...a4e097c1 - 7 commits from branch master
• 34e169a5 - Merge branch 'master' into fix/add-class-to-el-multiple-classes

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Looks as if this breaks the case where class is not a list, which it definitely was in the case for which the code was written. Your change assumes it is always a list. Please prove either point based on upstream docs or code.

resolved all threads

merged

mentioned in commit 29428e7b