The patch attached to this issue addresses two separate concerns (I did not want to open 2 issues for such small things):
1) Issue VWR-8624 allows the users to choose a set of default permissions and will be implemented in upcoming 1.23 release of the viewer.
Strangely enough, the current implementation does not honour "share with group" and "allow anyone to copy" for the snapshots. This is inconsistent with upload of sounds, animations and textures where these flags are honoured.
Here is the conceptual view I'd like to share:
permissions at creation time = (user-chosen defaults) OR (minimal permissions)
In this view, minimal permissions for snapshots are just more permissive than for textures, sound and animations.
2) PERM_MOVE is not set in user-defined next owner permissions for uploaded things. If this is not done here, it's fixed later by "fair use" rules for permissions, but it's cleaner to have it set correctly from the very beginning. This patch does that too.