Added new conversion functions from latest resolver libraries.
Stewart Brodie authored
Detail:
  New function inet_net_ntop, inet_net_pton, inet_ntop, inet_pton
    added.  These are thread-safe versions of other functions and
    should be used in preference to things like inet_ntoa, inet_aton.
    These functions are IPv6 aware - pass AF_INET6 to them if you
    want IPv6 operations, pass AF_INET if you want IPv4 (ie. current
    behaviour).
  Extra address family, protocol family definitions added for IPv6
    (and others since they were there in the FreeBSD headers),
    specifically: AF_INET6, PF_INET6, IN6ADDRSZ.  Corresponding
    extra DNS record types (T_AAAA) have been added too.
  APIs are standard APIs - documentation added to LibraryDoc.
  New inetlib/c/* files also contain their own documentation.
Admin:
  Required by TFTPserver (RISC OS version)
  Note: addition of these macros to the header file does *not* imply
    that the Internet module now supports IPv6.  These are header
    file macros added for the benefi...
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