Do not fire onChange in paragraph styles
dropdown when setting the value programmatically.
Apply paragraph style to all paragraphs in the cursor
selection.

* Modify OdtDocument.convertDomPointToCursorStep(),
which takes a node, an offset, and a boolean, and returns the steps to
that position from the root, rounded to the next allowed
position if the boolean is true, otherwise to the previous.

* Use this method in EditorSession.setCurrentParagraphStyle().
Merge pull request #215 from adityab/pstyle-multiparagraph

Apply paragraph style to all paragraphs in the cursor's selection