text:outline-level must be larger than 0.

[matus.uzak at gmail.com]

Hello again Jos,

do you have any test files, where text:outline-level is set to zero?
That means no paragraph styles to format TOC were found.  And I would
like to fix that.

-        cwriter->addAttribute("text:outline-level", levels);
+        if (levels > 0) {
+            cwriter->addAttribute("text:outline-level", levels);
+        }