Previously data/odt/content.xml contained only "Hello World!", so the
reference.odt produced by `--print-default-data-file reference.odt` gave
users no visual indication of which styles pandoc uses or how their
customizations would render.
Populate content.xml with example content exercising the predefined
paragraph and text styles shipped in data/odt/styles.xml: Author, Date,
Abstract, Heading_20_1..6, First_20_paragraph, Text_20_body (with
Emphasis, Strong_20_Emphasis, Strikeout, Superscript, Subscript,
Source_20_Text, Highlighted, hyperlink, and footnote), Quotations,
Preformatted_20_Text, List_20_Bullet, List_20_Number, TableCaption,
a two-column table using Table_20_Heading and Table_20_Contents,
FigureCaption, Definition_20_Term, and Definition_20_Definition.
This mirrors the demonstration content already present in
data/docx/word/document.xml.
Closes#10327.
The ODF validator complains about an invalid attribute
style:contextual-spacing in styles.xml, ultimately an implementation
error in whatever old version of LibreOffice that produced the
data/odt/styles.xml (should have put it into an extension namespace).
Fortunately the attribute was added to ODF 1.3, which was released a
couple years ago.
So the easiest fix is to simply produce ODF 1.3 instead of 1.2; it's
supposed to be fully backward compatible.
John MacFarlane