Addition of new strings in ppdippstr.py and new french translation

[LAfricain]

I just update the fr.po with the new strings.

[LAfricain]

Hello,
What about this pull request?
In this pull request there are some translated lines that are relatively important, namely about the two side print. Many users ask me how to do it or simply think that it is not possible because the field is not translated. Long edge/short edge, for a non-English speaking person means nothing. So it would be great to merge this query to be able to translate the line.