Digest auth: escape user names with \ or " in them

When sending the HTTP Authorization: header for digest, the user name
needs to be escaped if it contains a double-quote or backslash.

Test 1229 was added to verify

Reported and fixed by: Nach M. S
Bug: http://curl.haxx.se/bug/view.cgi?id=1230
curl.1: clarify that --silent still outputs data
curl_formadd.3: fixed wrong "end-marker" syntax

Reported and fixed by: Eric S. Raymond
Bug: http://curl.haxx.se/bug/view.cgi?id=1233
libcurl-tutorial.3: remove incorrect backslash

A single backslash in the content is not legal nroff syntax.

Reported and fixed by: Eric S. Raymond
Bug: http://curl.haxx.se/bug/view.cgi?id=1234
multi_runsingle: add braces to clarify the code
curl_setup.h: Fixed redefinition warning using mingw-w64
curl_schannel.c: Removed variable unused since 35874298e4
multi_runsingle: switch an if() condition for readability

... because there's an identical check right next to it so using the
operators in the check in the same order increases readability.
curl_multi_wait: reduce timeout if the multi handle wants to

If the multi handle's pending timeout is less than what is passed into
this function, it will now opt to use the shorter time anyway since it
is a very good hint that the handle wants to process something in a
shorter time than what otherwise would happen.

curl_multi_wait.3 was updated accordingly to clarify

This is the reason for bug #1224

Bug: http://curl.haxx.se/bug/view.cgi?id=1224
Reported-by: Andrii Moiseiev
libcurl-tutorial.3: added a section on IPv6

Also added a (correctly-escaped) backslash to the autoexec.bat
example file and a new Windows character device name with
a colon as examples of other characters that are special
and potentially dangerous (this reverts and reworks commit
7d8d2a54).
curl_multi_wait: only use internal timer if not -1

commit 29bf0598aad5 introduced a problem when the "internal" timeout is
prefered to the given if shorter, as it didn't consider the case where
-1 was returned. Now the internal timeout is only considered if not -1.

Reported-by: Tor Arntsen
Bug: http://curl.haxx.se/mail/lib-2013-06/0015.html
sws: support extracting test number from CONNECT ipv6-address!

If an ipv6-address is provided to CONNECT, the last hexadecimal group in
the address will be used as the test number! For example the address
"[1234::ff]" would be treated as test case 255.
test1230: verify CONNECT to a numerical ipv6-address
tests/Makefile: typo in the perlcheck target

Bug: http://curl.haxx.se/bug/view.cgi?id=1239
Reported-by: Christian Weisgerber
lib1500: remove bad check

After curl_multi_wait() returns, this test checked that we got exactly
one file descriptor told to read from, but we cannot be sure that is
true. curl_multi_wait() will sometimes return earlier without any file
descriptor to handle, just just because it is a suitable time to call
*perform().

This problem showed up with commit 29bf0598.

Bug: http://curl.haxx.se/mail/lib-2013-06/0029.html
Reported-by: Fabian Keil
RELEASE-NOTES: synced with 87cf677eca55

Added 11 bugs and 7 contributors
curl_easy_setopt.3: HTTP header with no content

Update the documentation on how to specify a HTTP header with no
content.
axtls: honor disabled VERIFYHOST

When VERIFYHOST == 0, libcurl should let invalid certificates to pass.
cert_stuff: remove code duplication in the pkcs12 logic
cert_stuff: avoid double free in the PKCS12 code

In the pkcs12 code, we get a list of x509 records returned from
PKCS12_parse but when iterating over the list and passing each to
SSL_CTX_add_extra_chain_cert() we didn't also properly remove them from
the "stack", which made them get freed twice (both in sk_X509_pop_free()
and then later in SSL_CTX_free).

This isn't really documented anywhere...

Bug: http://curl.haxx.se/bug/view.cgi?id=1236
Reported-by: Nikaiw