Rebuilding tree fails the first time in several occasions

[chkw-rks]

• when starting the server, "Build Tree" on the RootNode has to be triggered twice
• when introducing a SynthDef process for the first time, but only if that process has not been added anytime before in that document

[cnisidis]

partially solved in 0.0.4, it doesn't build the first time it boots the server, it is essential to connect and disconnect the first node from the root to trigger the BuildTree function.