Handle relative paths in Markdown export

[laurent22]

https://discourse.joplin.cozic.net/t/display-images-correctly-with-markdown-export/706/7

[GIT-STATA]

Hi laurent22,

thanks so much for your great work! I really appreciate all of it!

Right now I do not find any way for using a absolute or relative path, that is portable between Mac, Linux or Windows. It would be great to even implement that possibility in Joplin!

It would be great to enhance this feature that way, that you could use a relative path in the first place to write md files in Joplin as well! In editors like ATOM or SUBLIME TEXT you already can use a relative path for pictures or file attachments. That way you could keep your directory infrastructure as well as your 'naming conventions'.

For example, we use
![Picture-Definition-Year-Month](../relative_path/Illustrations/YEAR/MONTH/some_pic.jpg)

Many thanks again!

[forcewake]

Yep, @laurent22 thanks a lot!

Regarding the relative paths in the export.
In the current implementation there is only one issue - find the way to determine the level of _resources folder, due to notebooks hierarchy

or change the way how the images (or resources in general) are stored.

Second option can break some compatibility for users which are already rely on specific folder structure.

[laurent22]

@GIT-STATA, this is unlikely to be implemented since the recommended way to include a file is to attach it rather than link to a local file (that way it is synced with the notes). If you want to link to a local file you can already do so using the file:/// protocol. You would just need to make sure that all your devices have the same path structure, using symlinks if necessary.

[GIT-STATA]

@laurent22
Thanks a lot! I really appreciate all of your efforts!

Still if I do use the file:/// protocol I can't use a local path
like that one:

C:\Program Files\YEAR\M.01\DAY.jpg

A fix for #906 was merged!
I guess, that should solve those problems?

Thanks again!