Log Message:
links{,-gui}: Update to 2.18

Changes:
=== RELEASE 2.18 ===
- Compile links with graphics support on OpenVMS
- Automatically enable tor mode when the socks port is 9050
- When we are in tor mode, invert the colors on the top line and bottom
  line, so that the user can immediatelly see it
- Fix an incorrect shift in write_ev_queue that could cause spurious error
  if the socket for interprocess communication fills up.
  This bug was introduced in Links 2.15.
- Fix 'runtime error: member access within null pointer' sanitizer warning
- Add a menu entry to save and load a clipboard
- Don't synchronize with the Xserver on every pixmap load
  It improves performance on remote connections
- Fix a bug that in the "Network options" dialog box, the value in the
  field "Timeout when trying multiple addresses" incorrectly set the value
  "Timeout when unrestartable".
- Fix a possible integer overflow in decoder_memory_expand
- Work around a bug on OpenVMS where allocations larger than 0x77fffff0
  are treated as if they had 16 bytes
- Fix possible pointer arithmetics bugs if the operating system allocated
  memory few bytes below the limit 0xffffffff or 0xffffffffffffffff
- Add a button to never accept invalid certificate for a given server
- Fix incorrect strings -html-t-text-color, -html-t-link-color,
  -html-t-background-color, -html-t-ignore-document-color in the manual
  page and help (reported by Oliver Schode <oliver.schode@online.de>)
- Windows 7 has a bug (or feature) that corrupts the screen when using the
  unaccelerated video driver - when a thread draws into window's device context
  and the user simultaneously drags the window, the device context coordinates
  may not be updated. Subsequent draws are done with incorrect coordinates.
  In order to work around this bug, we detect that a drawing operation
  possibly raced with window moving. If it did, we allocate a new DC (the
  old one is corrupted) and start a timer that asks the main thread to
  redraw the whole window using the new DC.
- Add ascii replacement of Romanian S and T with comma
  Fix replacement of c with cedilla and a/i with grave accent a/o/u with
  diaeresis
- Use static linking in the released binaries on OS/2 because the DLL
  names may clash with other programs
- On OS/2, use AF_OS2 for interprocess communication because the loopback
  network device may not be properly configured.
  Fall back to 127.0.0.1 only if AF_OS2 in not installed.
- Fixed a bug when IPv6 control connection to a ftp server fails and IPv4
  control connection succeeds, links would incorrectly try to make the
  data connection using IPv6 (this bug was introduced in Links 2.15).