Images in PDF should be exported too

[ZedeX]

Is your feature request related to a problem? Please describe.
Images in PDFs should be exported too.

Describe the solution you'd like
Could export to a dir like filename-images, and file names could be like 00001~99999 (depends on how many images in the file. Or like YYMMDDHHMMSS-001.jpg, etc.), and link back to the md file with correct url.