Remove TODO for getopt.
Add statistical discard.
Make config. variables static.
Fix memory errors in tests, from leaks to heap corruption.

One specific lesson: don't corrupt the IHL of your IP header if
you want to check your checksum implementation.
Add session tests, and fix handling of duplicate packets.
Add Makefile for bmake, using prog.mk for now.
Clean up Makefile to avoid repeating common sources