Added unified description production, and also enforcing that desc matches in MAP/PEER delete (=> following RFC6887). Yay.
miniupnpd/pcpserver.c: fix ProcessPCPRequest()

fix commit 620af3737c8beffe87e08b7e0c34ab1661251695
miniupnpd: Added ENABLE_UPNPPINHOLE macro

using ENABLE_UPNPPINHOLE to compile in the support for IPv6 Firewall pinholes.
It is enabled by either ENABLE_6CF_SERVICE or ENABLE_PCP + ENABLE_IPV6.
Fixed PEER supporting PCP to compile too.
miniupnpd: Some initial effort at actually adding pinhole support to PCP code.
Added Linux get_pinhole_uid_by_index.
miniupnpd: work in progress on PCP pinhole support
Split Peer/Map logic to NAT- and FW specific parts. Updated TODO to include proxying.

+ fixes
Added TODO about IPv6 permission handling.
Checking lan only in non-thirdparty mode.
Made failed pinhole request actually fail in terms of return value too.
Added pcp_ prefix to allow_thirdparty option (options parsing reserved allow for it's own use).
miniupnpd/upnpsoap.c: Follow change in upnp_get_pinhole_info()
miniupnpd/pcpserver.c: prevent compiling with PCP_PEER on if not applicable