+ * Allow the exchange of 0-long dynamic vectors.
+ - for that, use -1 as indicator of dynamic size instead of 0
+ - This implied to change any size from unsigned long to long,
+ reducing a bit communication abilities, but I guess that with
+ 64bits being quite common, this is more than enough.
+ - This also induce a protocol change, thus bumping network protocol
+ version from 0 to 1 (if we have external users, we have to get
+ clean on that point too ;)