Log Message:
Update to 2.1a13, from Geert Hendrickx and William Fletcher.
arpwatch changes:
- Convert arp2ethers from csh to sh
- updated ethercode.dat
- misc minor bugfixes

Changes from Geert Hendrickx:
- move ethercodes.dat to share/arpwatch (from etc)
- Use ${VARBASE:Q} instead of ${VARBASE} as suggested by pkglint
 - Use OWN_DIRS to note the admin about the stale db directory after
   deinstallation
Changes from William Fletcher:
- add a rc.d script
- add a '-m' option to specify the recipient for email messages (still
  defaults to root)

Fix pkg/32151 by Geert Hendrickx