World snapshot/restoration

[willneedit]

ref- #135

Self explanatory. Likely because of the changing CID while changing its data, we can simply record the CIDs... And keeping snapshots can be done with pinning or leaving it unpinned, or keeping it a DAG node, like a directory.

Maybe with a DAG node, because it can be tied to names or other metadata.

[willneedit]

Just changing the WorldInfo's changed creation time causes the CID to change, causing another copy of the world to pop up.

That could be a problem of flooding the world panel with half-finished versions.

Maybe a fixed creation time, with a "update creation time" button...? 🤔