Small fixes for IE10

Wodo.TextEditor does still not completely work after this, but at least better then before.
Also makes ViewerJS in IE properly display ODT with annotations.

Any IE lovers around to continue this work? I somehow feel unmotivated for more ;)
parentElement is only a problem on non-element nodes, which should not be a problem in those cases from what I saw before. Do you think it would still be better to change that to parentNode, to avoid new problems due to copy&paste for new code?