Feature request: Being able to submit custom images

[stucka]

Euchre now only works with stock art that's supplied to the server before the code is launched. It would be very helpful to be able to upload custom art, but that's not implemented yet. Such custom art would be helpful to be able to work in bulk. A couple potential approaches:

-- Detect if the user has selected a custom art option, and then request the image if needed. This opens the door to potential abuse (e.g., server gets full of downloaded images).

-- Require any custom images be sent with each instance within a multipart POST request. This increases the complexity of programmatic client access and eliminates the potential to cache images.

If caching images, a thought: On each generate, check the cache/downloaded images directory and purge all files older than, say, five minutes. If the requested filename is available after that, assume it's correct and use it.

[stucka]

Alternately: Being able to upload an image by way of a submitted URL.

All these need to be thought through as far as sanitizing data inputs and preventing intentional or unintentional denial of service.