ports. Given that you import port once but update it a few times, make
the update mode (-CU) default for portcheck, and provide a "new port"
switch (-N) instead.
This commit updates portcheck(1) and portimport(1): code, documentation and
tests. The WWW stuff will be updated separately.
Note: regression suite fails now as it detected an actual misconsistence
in portcheck's output. This will be handled ASAP, too.
Initial prodding by naddy@
