LoadGen: Small fixes.
Removed noisy printout in basic_apps.
New cmdline: snabbswitch [options] <module> [args...]

That is: module name is mandatory and any extra arguments are
collected and stored in table core.main.parameters for reference.

The module would typically e.g. designs.loadgen.loadgen.
Must find a way to shorten those...
loadgen cmdline: <filename> [nic...]

Each nic parameter is a Lua pattern that can match a PCI address.

Example:
  foo.pcap                              # Use all NICs (no patterns)
  foo.pcap 0000:0a:00.1 0000:8a:00.1    # use two NICs, one from each CPU
  foo.pcap      0a:00.1      8a:00.1    #   (shorter version)
  foo.pcap 0000:0                       # use all NICs from CPU 0 (by prefix)
  foo.pcap 0000:8                       # use all NICs from CPU 1 (by prefix)