JSON parsing: block unlinking

[Conaclos]

Severity: Low (current assessment)

Problem

When a block is splited on two nodes or more, each node keep a reference to the same block. This enables to each one to edit it.

The object-to-JSON transformation breaks this single reference into several plain objects.
During the JSON-to-object parsing, a (previously) splited block is then represented by several blocks.

Symptoms

The garbage collection of the splited blocks is compromised.
It is not a severe symptom.

Other symptoms are not detected yet.

Possible fix

Remove the block from the nodes and only retains the base of the block'id.
The block is then modified from the base-to-block mapping in logootsropes.

This also implies to move the code that tests if a block is appendable.
Or, maybe two simple flags (isAppendable, isPrependable) for each node is ok?