.odt support

[HR]

This issue is to track the .odt format implementation progress

[ferndot]

We can use http://webodf.org/!

[twiss]

Unsupported odt features by #261:

• [ ] Breaks editing
  • [ ] Annotations
  • [x] Footnotes
  • [ ] Tracked changes
  • [ ] Charts
• [ ] Doesn't break editing
  • [ ] Various types of images
  • [ ] Non-"manual" styles
  • [ ] Unordered lists
  • [ ] List styles (bullets,)
  • [ ] Strikethrough
  • [ ] Underlined text nested inside non-underlined text
  • [ ] Underline-color
  • [ ] Loads of other styles

And probably much more.