* Fix generating libreswan versions based of git

And remove support for obsolete versions of git
* Updated ipsec showhostkey to support IPSECKEY

Also removed support for KEY and TXT record, and removed stub
options for x509 options that were not implemented.
* Fixup IPSECKEY support with ipv4/ipv6 family and support --precedence

Also updated the man page to reflect the changes made.
whitespace changes
* Remove support for Linux kernels < 2.1.0 via NET_21 define
* Remove support for kernels without SPINLOCK and SPINLOCK_23

    These are all pre 2.4 kernels.
* Remove more old 2.1 and 2.3 kernel code
* Remove /proc support pre-2.4 kernels (PROC_FS_2325/PROC_FS_21)
* Remove kernel support predating NETLINK
* Remove support for NET_23 (kernels before 2.3)
* Always add support for alias capability (CONFIG_IP_ALIAS)
* Remove /proc dummy code for old kernels (PROC_NO_DUMMY)
* Remove SKB_COPY_EXPAND for < 2.3 kernels
* Remove compat old/broken IP_SELECT_IDENT for < 2.4.2 kernels

    Also removes support for broken 2.4.19 suse kernels
* Remove compat code for SKB_COW_NEW for < 2.4.4. kernels
* Remove pre 2.4.4 kernel compat for PROTO_HANDLER_SINGLE_PARM
* Remove pre 2.4.4 IP_FRAGMENT_LINEARIZE compat code
* Remove remaining pre 2.4.4 kernel support
* Remove support for kernels not supporting MALLOC_SLAB
* Remove support for kernels without snprintf