+ SURF:
+ * Rename configuration variables to start a hierarchy:
+ o cpu_model -> cpu/model
+ o network_model -> network/model
+ o workstation_model -> workstation/model
+ * New configuration variables:
+ o network/bandwidth_factor: correction to bandwith
+ o network/latency_factor: correction to latency
+ o netwotk/weight_S: correction to the weight of competing streams