Bring over the 20141204 portable version of netpgpverify from pkgsrc

+ Remove unused logmessage helper function

+ Add pgpv_get_cursor_element for easier manipulation of results
returned.

+ libnetpgpverify(3) man page improvements

+ Standardise on WARNS=5 settings (6 is too intrusive and distracting)

+ Also install the library and header file for netpgpverify.  This
allows scripting languages to use the same verification methods via a
shared library, rather than being forced to exec the netpgpverify(1)
command line utility.

+ libnetpgpverify is now a standalone library, and requires no
pre-requsisite libraries to function
set up the netpgp lib directory hierarchy a bit more logically

+ move libnetpgp to the same level as libnetpgpverify

+ fix up all paths to the new directory structure