Support for relative links

[Maboroshy]

Hi! I'm using your app to view and edit files generated by the desktop appQOwnNotes. It is very well suited for such use, much more than any other Android md editors I could find in the market.

When inserting inline image QOwnNotes copies it to media subdirectory and puts a link like this name where directory is relative to md file.

Could you implement an option so MarkdownX would render such links. It will allow for inline images and other linked files to be portable.

[dlip]

+1 Draft android app does this nicely