Enforce security using editing session ids

[Chat-Wane]

Some troubles may arise from the save/load of files. Indeed, without this feature, a document exists only if at least one peer keeps it alive, i.e., does not close the browser tab. Thus, when he shares it, the document is fully replicated.

On the opposite, if someone joins the authoring of a document while a local file is already opened, some undesired behaviors can happen. For instance, it is to be expected that the files will merge and both documents will be corrupted, i.e., the characters of both documents are mixed together.

[Chat-Wane]

Must check the network session id.