MEDIUM: server: Don't load server-state file if a line is corrupted

MEDIUM: server: Don't load server-state file if a line is corrupted

This change is not huge but may have a visible impact for users. Now, if a
line of a server-state file is corrupted, the whole file is ignored. A
warning is emitted with the corrupted line number.

In fact, there is no way to recover from a corrupted line. A line is
considered as corrupted if it is too long (truncated line) or if it contains
the wrong number of arguments. In both cases, it means the file was forged
(or at least manually edited). It is safer to ignore it.

Note for now, memory allocation errors are not reported and the
corresponding line is silently ignored.