Commit d7223774 (abi#9930
DocxAttributeOutput::AddToAttrList: avoid duplicated attributes,
2014-11-02) added a quick fix to avoid writing duplicated attributes,
but the validation problem of duplicated elements remained.

Make sure that when writing paragraph marker properties, then we write
either the hints at the end of the paragraph or the character attributes
range of the paragraph properties, but not both.

The only exception is the character style that's always set as
a hint, as explained in commit 4bb872b1
(DOCX export: fix handling of paragraph mark on empty paragraphs,
2014-10-17).

Change-Id: I494e5bb9871aa535532fef32bd344d8093e9f762