ForkChannel needs to call init() and start() correctly on all added protocols

The attached program doesn't work because `RAFT.init()` tries to find `GMS` on the main stack, but `GMS` hasn't yet been created. Same issue with adding an `AddressGenerator` in `RAFT.init()`.

Is `start()` called at all on protocols added by `FORK` on top of the main channel ? Is `init()` called at the right time ?
The attached bla program reproduces the issue (in jgroups-raft).