Currently, when SVG image is loaded with `svg_load` it first examines :file
value and only if :file is missing it looks for :data, using current
buffer's filename (if any) as base_uri

Would not it be better to check for :data first and if present, then use
:file as value for base_uri?  Falling back to current buffer filename in
case :file is missing

Unfortunately embedding raster images into svg with base64 encoding, using
`svg-embed` is slow.

Thanks

-- 
lg