glycin-loaders rename

Hi all,

upstream renamed the glycin-loaders tarball providing the image loaders
for loupe to glycin since it now contains two shared libraries written
in Rust (cdylibs). I intend to mirror this change in Debian, too. Since
the two cdylibs will warrant a NEW trip anyway I will rename the source
package to glycin to better reflect that it's not just providing the
image loaders. Nothing will change for loupe as it will depend on the
binary package glycin-loaders.
.
I will go ahead with this change soon unless someone objects.

best,

werdahias