Exported rst contains a lot of duplicate definition names

[rduivenvoorde]

Current version of rst-export (dd 23rd may 2020), does not cleanly compile in Sphinx, giving errors like:

index.rst:1780:Duplicate substitution definition name: "image".

It appears that a lot of images are named 'image':

.. |image| image:: https://user-images.githubusercontent.com/127259/80964191-b4abcb80-8e10-11ea-8b80-395dbb37b45c.png
.. |image| image:: https://user-images.githubusercontent.com/16253859/80860629-47116b00-8c69-11ea-83d8-61f27cb77e68.png
.. |image| image:: https://user-images.githubusercontent.com/16253859/80860663-6c9e7480-8c69-11ea-94a3-8d0e8544867d.png
.. |image| image:: https://user-images.githubusercontent.com/16253859/80860675-7b852700-8c69-11ea-984d-584eff1e3c95.png
.. |image| image:: https://user-images.githubusercontent.com/16253859/81009703-653bbe80-8e55-11ea-9286-4850b32edb23.png
.. |image| image:: https://user-images.githubusercontent.com/1829991/80680381-faf7e680-8b01-11ea-8612-b0f543bfd943.png

Would be good to ensure that these are unique names (at least for the rst export)

[anitanh]

this issue has been fixed here #1195