Sync BufferWrites across clients

[Abh15h3k]

Currently if any client saves :w a file it is written only for that client (in his local directory).
Ideally this should also cause all clients to save the file.

[niveK77pur]

Ontop of that, it appears as though the syncing breaks after a client saves. The server no longer sees the client edits, and the client appears to be modifying its own copy.