Allow for storing images in original (or just higher) resolution (format?)

[yarikoptic]

ATM minder when embedding an image rescales it to the node size. Found #279 describing that. The problem is that I wanted to use minder to develop a sketch of a sizeable poster for a conference which I would then export to .svg for the final tune ups. I embedded a bunch of images into minder map but export to svg/opening them in inkscape showed them to be in very lousy resolution.

I think if minder had a notion of resolution (some kind of "dpi") for the drawing, and then based its scaling/size of images to embed - that would have been nice! An alternative is may be to have an option for .svg export to just link to the external images instead of embedding? I see that minder does retain the map for images to original locations, so just a matter of using them I guess:

 <images>
    <image id="8" uri="file:///home/yoh/proj/datalad/artwork/logos/logo_wide.svg" ext=".svg"/>
    <image id="9" uri="" ext=".png"/>
    <image id="10" uri="file:///tmp/logo_small.png" ext=".png"/>
    <image id="11" uri="file:///tmp/logo@2x.png" ext=".png"/>
    <image id="12" uri="file:///home/yoh/proj/CON/talks/2022-nih-compcore/pics/BIDS_Logo.png" ext=".png"/>
    <image id="15" uri="file:///home/yoh/proj/open-brain-consent/docs/source/_static/OBC_LogoCheck.svg" ext=".svg"/>
    <image id="16" uri="file:///home/yoh/proj/CON/talks/pics/datacat4_the_catalog.svg" ext=".svg"/>
    <image id="17" uri="file:///home/yoh/proj/CON/talks/pics/datalad-gooey-1.png" ext=".png"/>
    <image id="18" uri="file:///home/yoh/proj/CON/talks/pics/datalad-usage-dashboard-inwild-20221024.png" ext=".png"/>
    <image id="19" uri="file:///home/yoh/proj/CON/talks/pics/git-annex-status.png" ext=".png"/>
    <image id="20" uri="file:///home/yoh/proj/CON/talks/pics/datalad-extensions.png" ext=".png"/>
  </images>

ATM I would need to export to .svg and then go and replace every image with original version of it at higher resolution. Tedious... May be you see some "shortcut" to e.g. quickly gain referencing of external images? ;)