USB-storage: after ACK free Packet_descriptor
tool: simple trace visualizer script

It uses a GNU awk script to generate a .dot file from a trace logfile
and creates an image.
tool: simple converter for trace-viewer
os: add Trace_fs
ports: add noux trace_fs run-script
os: stand-alone snprintf() for trace-policies
os: example Policy::snprintf policy
os: add policy for tracing RPC alloc and free