Merge the 0.68 release branchlet to master.

Conflicts in the FAQ are fixed by incorporating Jacob's rewritten
post-0.68 version. (But owing to considerable git confusion I haven't
managed to get his name on to this commit anywhere.)

diff --cc doc/faq.but
index 6c41bd4affd792d50294c391df90345686f25e41,ba0d53213f3568011122e39cf192c8c615252800..42f965b272a0631ce3ca8e4e20a0596c4108f24b
--- 1/doc/faq.but
--- 2/doc/faq.but
+++ b/doc/faq.but
@@@ -216,16 -215,17 +215,12 @@@ seems to be working so far
  Currently, release versions of PuTTY tools only run on Windows
  systems and Unix.
  
- \#{XXX-REVIEW-BEFORE-RELEASE: replace following two lines with:
--As of 0.68, the supplied PuTTY executables run on versions of
- Windows from XP onwards,}
- PuTTY runs on versions of Windows from Windows 95 onwards (but not
- the 16-bit Windows 3.1; see \k{faq-win31}),
- up to and including Windows 10; and we know of no reason why PuTTY
- should not continue to work on future versions of Windows.
- \#{XXX-REVIEW-BEFORE-RELEASE: We provide 32-bit and 64-bit Windows
- executables; see \k{faq-32bit-64bit} for discussion of the
- compatibility issues around that.}
 -Windows from XP onwards, up to and including Windows 10; and we
 -know of no reason why PuTTY should not continue to work on
 -future versions of Windows.
 -
 -The 32-bit Windows executables we provide for the \q{\i{x86}}
 -processor architecture should also work fine on 64-bit processors
 -that are backward-compatible with that architecture. The 64-bit
 -executables will only work on 64-bit versions of Windows. They
 -will run somewhat faster than 32-bit executables would on the
 -same processor, but will consume slightly more memory.
++As of 0.68, the supplied PuTTY executables run on versions of Windows
++from XP onwards, up to and including Windows 10; and we know of no
++reason why PuTTY should not continue to work on future versions of
++Windows. We provide 32-bit and 64-bit Windows executables; see
++\k{faq-32bit-64bit} for discussion of the compatibility issues around
++that.
  
  (We used to also provide executables for Windows for the Alpha
  processor, but stopped after 0.58 due to lack of interest.)
@@@ -583,29 -584,6 +577,28 @@@ of quotes in the obvious way
  \c pscp "local file" user@host:
  \c pscp user@host:"remote file" .
  
- The 64-bit version
- \#{XXX-REVIEW-BEFORE-RELEASE (first released in 0.XX)}
- will only run if you have a 64-bit processor \e{and} a \I{64-bit
- Windows}64-bit edition of Windows (both of these things are likely to
- be true of any recent Windows PC). It will run somewhat faster (in
- particular, the cryptography will be faster, especially during link
- setup), but it will consume slightly more memory.
 +\S{faq-32bit-64bit}{Question} Should I run the 32-bit or the
 +64-bit version?
 +
 +If you're not sure, the \I{32-bit Windows}32-bit version is generally
 +the safe option. It will run perfectly well on all processors and on
 +all versions of Windows that PuTTY supports. PuTTY doesn't require to
 +run as a 64-bit application to work well, and having a 32-bit PuTTY on
 +a 64-bit system isn't likely to cause you any trouble.
 +
++The 64-bit version (first released in 0.68) will only run if you have
++a 64-bit processor \e{and} a \I{64-bit Windows}64-bit edition of
++Windows (both of these things are likely to be true of any recent
++Windows PC). It will run somewhat faster (in particular, the
++cryptography will be faster, especially during link setup), but it
++will consume slightly more memory.
 +
 +If you need to use an external \i{DLL} for GSSAPI authentication, that
 +DLL may only be available in a 32-bit or 64-bit form, and that will
 +dictate the version of PuTTY you need to use. (You will probably know
 +if you're doing this; see \k{config-ssh-auth-gssapi-libraries} in the
 +documentation.)
 +
  \H{faq-trouble} Troubleshooting
  
  \S{faq-incorrect-mac}{Question} Why do I see \q{Incorrect MAC