ServerTree register actions to be taken to initialise a basic tree of groups on the server

Inherits from: Object : AbstractSystemAction : AbstractServerAction

The singleton ServerTree provides a place for registering functions and objects for

events that should happen when a given server has booted and when all synths are freed.

This is to initialise a basic tree of groups on the server.

See also: Server, ServerQuit, ServerBoot, CmdPeriod