Option to download original, full-res images

[philwilei]

I implemented an option to make the original image files downloadable at full resolution:

I created this to be able to distribute photos I took at a family event to all the participants. This way everyone could easily choose the photos they liked and download them at original quality, which saved me from having to transfer large files to individuals one by one.

This feature might also appeal to professional photographers looking to host their own delivery platform so they don't have to rely on paid services like Pixieset.

The feature is off by default and can be enabled by setting the ALLOW_ORIGINAL_DOWNLOAD environment variable to 1. In the gallery view, a download button will show up in the bottom right corner of a hovered image. In single-photo view, the download button is permanently visible in the top right corner.

Maybe this is outside the scope of this project (in which case, I don't mind if it doesn't get merged), but I thought that others might find this useful too.

[waschinski]

That's a nice feature, Philipp, thank you very much for the PR!