MODE 1972 Updated the copy operation so that it's possible to copy entire workspaces, but not possible to copy a subgraph from a source workspace into a target workspace root.
MODE 1972 Updated the clone operation so that it's possible to clone and entire workspace into another workspace. The root node, together with the system nodes are excluded from both clone & copy.
MODE-1978 Corrected the WritableSessionCache to fix NPE from recently-added code

A recent fix for MODE-1940 added code that updated the indexes if the
new parent was persisted (previously) and the child was moved. In some
cases when the new parent was not persisted in a previous save but instead
was created as part of this save, the code resulted in an NPE. The fix
was a simple change.

A test case was added to first replicate the problem. After the change,
the test now succeeds (and the S-RAMP build works completely).