If a core Wireshark developer repeatedly can't remember that the

If a core Wireshark developer repeatedly can't remember that the
argument to the -F flag for pcap format is "libpcap", not "pcap", we
have a problem.  Make it "pcap", and add a backwards-compatibility hack
to support using "libpcap" as well.

Update the man pages to refer to it as pcap as well, and fix the
capitalization of "WinPcap" (see http://www.winpcap.org) while we're at
it.

Also, refer to http://www.tcpdump.org/linktypes.html for the list of
link-layer header types for pcap and pcap-ng.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@50989 f5534014-38df-0310-8fa8-9805f1628bb7