Now that WinPcap is a DLL, I can load it at run-time rather than load-time.

Now that WinPcap is a DLL, I can load it at run-time rather than load-time.
That means that I no longer need to distribute capture and non-capture
versions of Ethereal for Win32; one version (compiled with WinPcap headers)
can run on systems with or without WinPcap.

For systems that don't have WinPcap, instead of disabling the Capture
menu, Capture|Start brings up a dialogue informing the user that wpcap.dll
was not loadable, and gives a URL to the WinPcap home page.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@3249 f5534014-38df-0310-8fa8-9805f1628bb7