Make OdtDocument.convertDomToCursorRange
accept two more boolean arguments, indicating
the rounding direction at each endpoint.

In SessionController.selectRange's call to
OdtDocument.convertDomToCursorRange, fix it
to restrict the computed cursor range to never
overflow outside of the originally supplied
range.
This fixes issues where indenting/paragraph-styling
completely-selected paragraphs (that had their
beginnings already direct-styled) would also
indent/style their previous paragraphs.

Thus, triple-click selection no longer bleeds
into the surrounding paragraphs.