Refactored command-line parsing to use getopt.

Conflicts:
	src/ipop_tap.c
Added strlcpy from OpenBSD

Used it to correct buffer underrun errors in the parsing of the
configuration file.

Conflicts:
	src/ipop_tap.c
Remove old BAD_ARG macro

The "cleanup" commit that Thomas originally had fixed this, but that
commit has tons of other changes that are hard to apply on top of the
latest HEAD.
Merge pull request #4 from ipop-project/thom-changeset

Thomas' Changeset (from a year ago)