Automatic image naming when saving

[VictorZakharov]

For image naming, the formatter should support at minimum two entities, original article file name without md extension, like {filename} and sequential number {seq} which would be generated dynamically, based on already generated files (on the file system). And then I could specify {filename}-{seq} as image name format and not have to worry about opening any external windows (or just click confirm, because the image name would be correct every time). Very important for focus on writing great content (much like code).

The rationale for such naming scheme is that I should be able to know which article the image refers to by looking at the image file only. For example, if I were to delete an article, which images I need to delete, I could tell by file name. If it was some random name or guid based, I would need to see which images are referenced, what their names are, and then delete one by one (lots of back and forth).

I think by default the image save folder should be ProjectWebRoot we discussed in #619. And perhaps after this change I no longer need to open a dialog with prompt, so it could paste the image and then if necessary I can click that image to change path via image props or something like that (but realistically this would never happen assuming the naming algo is working correctly). This could be another/unrelated change with less priority.