onWelcome

Does three things upon RPL_WELCOME;

1. Sets up the FIFO pipe, resolving the filename and creating it. 2. Prints the usage text. 3. Lastly, endlessly loops (as a Fiber) and checks once per hour if the FIFO has disappeared, and recreates it if so. This is to allow for recovery from the FIFO being deleted.

Initialises the FIFO *here*, where we know our nickname (we don't in .initialise).

version(Posix && WithPipelinePlugin)
private
void
onWelcome