Fix relative file paths in plists

[intrications]

libreliodev/javascript#195 (comment)

On iOS, no extra development was needed because there is a notion of relative reference. So for example, if there is a reference to pdfname/pdfname.pdf from a plist located in the dir directory, then the app will understand that pdfname is at dir/pdfname/pdfname.pdf.

[intrications]

#252 (comment)

[intrications]

Implemented but leaving this issue open to remind me to test on other customizations.