pcap.lua uses pf.lua types

* src/pf.lua: Redefine BPF type using the struct name that pcap uses.
  Export the bpf_insn and bpf_program types.  Redirect multiplications
  to a runtime function.  Simplify fallthroughs for branches.  Add error
  if we fall off the end of the program.

* src/pcap.lua: Use the bpf_insn and bpf_program types from pf.lua.
Filter compilation works without root privileges

* src/pcap.lua: Fix to work without root privileges by using
  pcap_open_dead.
Further pcap.lua tweaks

* src/pcap.lua: pcap_compile returns the program or fails, without
  reboxing the bytecode.  dump_bytecode does something nicer.
Fold pcap.lua into pf.lua

* src/pf.lua: Fold pcap.lua into pf.lua, as we need to test these
  together.

* src/Makefile: Update.
Initial steps to working code generation

* src/pf.lua: Fix code generation.
More code generation tweaks

* src/pf.lua (bpf_program): Fix return generation, and add P parameter.
Actually loading generated function

* src/pf.lua: Nicer formatting.  Fix goto syntax.  Fix return syntax to
  conform to Lua's weirdness.  Test loading up the function.
More testing, fix rsh

* src/pf.lua: Test a more complicated string.  Fix a bug in RSH
  support.
Small optimizations

* src/pf.lua: Optimize MSH and JEQ.