do not add text-box on images without label on ODT generator

I implemented on my fork branch, a change to ODT to not add a text-box if it adds an image without label:
https://github.com/KammutierSpule/MultiMarkdown-5/commit/6c23c7cd7df74d5df294a067ca13efa99f3c16af

Adding a text-box on inline text causes the image to be placed incorrectly because Libreoffice? is adding (automatic) padding, so the image will appear up line with the text.
