Package action to remove unused images from image folder

[chrahunt]

I use this extension a lot for notes, and often take screenshots to embed in the notes themselves. I currently use the file in folder setting and It can be kind of a pain to refactor notes and have to worry about going back into the images folder and deleting the unused images.

Would it be possible to add a feature to go through and remove unused images from the images folder? Get the list of files in the folder that would correspond to this markdown document, get the list of images referenced in the document, take the diff and prompt for deletion. I don't see an obvious reason to have anything other than a simple dialog with a list of the images to be deleted and asking for confirmation, but others may have different requirements. For user comfort, it could also mention the number of images that were found in the images folder that are used in the current document, just so people can see the correct folder was selected.

I could see this going in either the context menu for a document tab, or available from Packages > Markclip.

[csbun]

Please feel free to make a pull request. O(∩_∩)O~