Curl and libcurl 7.52.0

 Public curl releases:         161
 Command line options:         203
 curl_easy_setopt() options:   243
 Public functions in libcurl:  61
 Contributors:                 1467

This release includes the following changes:

 o nss: map CURL_SSLVERSION_DEFAULT to NSS default
 o vtls: support TLS 1.3 via CURL_SSLVERSION_TLSv1_3
 o curl: introduce the --tlsv1.3 option to force TLS 1.3
 o curl: Add --retry-connrefused [11]
 o proxy: Support HTTPS proxy and SOCKS+HTTP(s) [24]
 o add CURLINFO_SCHEME, CURLINFO_PROTOCOL, and %{scheme} [20]

This release includes the following bugfixes:

 o msvc: removed a straggling reference to strequal.c
 o winbuild: remove strcase.obj from curl build [1]
 o examples: bugfixed multi-uv.c
 o configure: verify that compiler groks -Werror=partial-availability [2]
 o mbedtls: fix build with mbedtls versions < 2.4.0 [3]
 o dist: add unit test CMakeLists.txt to the tarball
 o curl -w: added more decimal digits to timing counters [4]
 o easy: Initialize info variables on easy init and duphandle [5]
 o cmake: disable poll for macOS [6]
 o http2: Don't send header fields prohibited by HTTP/2 spec [7]
 o ssh: check md5 fingerprints case insensitively (regression) [8]
 o openssl: initial TLS 1.3 adaptions
 o curl_formadd.3: *_FILECONTENT and *_FILE need the file to be kept
 o printf: fix ".*f" handling [9]
 o examples/fileupload.c: fclose the file as well
 o SPNEGO: Fix memory leak when authentication fails [10]
 o realloc: use Curl_saferealloc to avoid common mistakes [12]
 o openssl: make sure to fail in the unlikely event that PRNG seeding fails
 o URL-parser: for file://[host]/ URLs, the [host] must be localhost [13]
 o timeval: prefer time_t to hold seconds instead of long
 o Curl_rand: fixed and moved to rand.c [14]
 o curl: add --fail-early [15]
 o glob: fix [a-c] globbing regression [16]
 o darwinssl: fix SSL client certificate not found on MacOS Sierra [17]
 o curl.1: Clarify --dump-header only writes received headers
 o http2: Fix address sanitizer memcpy warning
 o http2: Use huge HTTP/2 windows [18]
 o connects: Don't mix unix domain sockets with regular ones
 o url: Fix conn reuse for local ports and interfaces [19]
 o x509: Limit ASN.1 structure sizes to 256K
 o checksrc: add more checks
 o winbuild: add config option ENABLE_NGHTTP2 [21]
 o http2: check nghttp2_session_set_local_window_size exists [22]
 o http2: Fix crashes when parent stream gets aborted [23]
 o CURLOPT_CONNECT_TO: Skip non-matching "connect-to" entries [25]
 o URL parser: reject non-numerical port numbers
 o CONNECT: reject TE or CL in 2xx responses
 o CONNECT: read responses one byte at a time [26]
 o curl: support zero-length argument strings in config files [27]
 o openssl: don't use OpenSSL's ERR_PACK [28]

This release includes the following known bugs:

 o see docs/KNOWN_BUGS (https://curl.haxx.se/docs/knownbugs.html)

This release would not have looked like this without help, code, reports and
advice from friends like these:

  Adam Langley, Adam Piggott, afrind on github, Alex Chan, Alex Rousskov,
  Anders Bakken, Andrei Sedoi, Bruce Stephens, Dan Fandrich, Daniel Hwang,
  Daniel Stenberg, Dave Reisner, David Schweikert, Dmitry Kurochkin,
  Frank Gevaerts, Isaac Boukris, Jakub Zakrzewski, Jan Ehrhardt,
  Jeremy Pearson, Kamil Dudka, Marcel Raad, Mauro Rappa, Michael Kaufmann,
  Mike Crowe, Neal Poole, Nick Zitzmann, Okhin Vasilij, Patrick Monnerat,
  Peter Wu, Ray Satiro, Ricki Hirner, Tatsuhiro Tsujikawa, Thomas Glanzmann,
  Tony Kelman, Vasy Okhin,
  (35 contributors)

        Thanks! (and sorry if I forgot to mention someone)

References to bug reports and discussions on issues:

 [1] = https://curl.haxx.se/bug/?i=1098
 [2] = https://curl.haxx.se/bug/?i=1104
 [3] = https://curl.haxx.se/bug/?i=1087
 [4] = https://curl.haxx.se/bug/?i=1106
 [5] = https://curl.haxx.se/bug/?i=1103
 [6] = https://curl.haxx.se/bug/?i=1089
 [7] = https://curl.haxx.se/bug/?i=1092
 [8] = https://github.com/curl/curl/commit/ce8d09483eea2fcb1b50e323e1a8ed1f3613b2e3#commitcomment-19666146
 [9] = https://curl.haxx.se/bug/?i=1113
 [10] = https://curl.haxx.se/bug/?i=1115
 [11] = https://curl.haxx.se/bug/?i=1064
 [12] = https://curl.haxx.se/mail/lib-2016-11/0087.html
 [13] = https://curl.haxx.se/mail/lib-2016-11/0104.html
 [14] = https://curl.haxx.se/mail/lib-2016-11/0119.html
 [15] = https://curl.haxx.se/mail/archive-2016-11/0038.html
 [16] = https://github.com/curl/curl/commit/ee4f76606cfa4ee068bf28edd37c8dae7e8db317#commitcomment-19823146
 [17] = https://curl.haxx.se/bug/?i=1105
 [18] = https://curl.haxx.se/bug/?i=1102
 [19] = https://curl.haxx.se/mail/lib-2016-11/0137.html
 [20] = https://curl.haxx.se/bug/?i=1137
 [21] = https://curl.haxx.se/bug/?i=1141
 [22] = https://github.com/curl/curl/commit/a4d8888#commitcomment-19985676
 [23] = https://curl.haxx.se/bug/?i=1125
 [24] = https://curl.haxx.se/bug/?i=1127
 [25] = https://curl.haxx.se/bug/?i=1148
 [26] = https://curl.haxx.se/bug/?i=1132
 [27] = https://curl.haxx.se/bug/?i=1152
 [28] = https://curl.haxx.se/bug/?i=1157
