CID 1397391 (#1 of 1): Unchecked return value (CHECKED_RETURN)

Follow-up to d00f2a8f

- Check for pending data before waiting on the socket.

Bug: https://github.com/curl/curl/issues/1156
Reported-by: Adam Langley

Fixes a few issues in manual wildcard cert name validation in
schannel support code for Win32 CE:
- when comparing the wildcard name to the hostname, the wildcard
  character was removed from the cert name and the hostname
  was checked to see if it ended with the modified cert name.
  This allowed cert names like *.com to match the connection
  hostname. This violates recommendations from RFC 6125.
- when the wildcard name in the certificate is longer than the
  connection hostname, a buffer overread of the connection
  hostname buffer would occur during the comparison of the
  certificate name and the connection hostname.

... and add a bunch of floating point printf tests

and regenerated curl.1

Reported-by: Gisle Vanem

Follow-up to 82245eaa: Fix the example program sendrecv.c (handle
CURLE_AGAIN, handle incomplete send). Improve the documentation
for curl_easy_recv() and curl_easy_send().

Reviewed-by: Frank Meier
Assisted-by: Jay Satiro

See https://github.com/curl/curl/pull/1134

It doesn't benefit us much as the connection could get closed at
any time, and also by checking we lose the ability to determine
if the socket was closed by reading zero bytes.

Reported-by: Michael Kaufmann

Closes https://github.com/curl/curl/pull/1134

As the official docs seems really hard to keep track of and link to over
time

Fixed trailing whitespace and numerous formatting glitches

--krb4, --ftp-ssl and --ftp-ssl-reqd no longer need to be documented in the
man page

This is the first time we replace the manually edited curt.1 with the
generated one created by gen.pl and the individual option documentation
pages.

Do not edit this file, edit the individual pages and regenerate this
output.

This file will be generated by the build system soon and then removed
from git.

... to avoid people from trying to edit the pending curl.1 version that
gets generated by gen.pl

CURLOPT_SOCKS_PROXY -> CURLOPT_PRE_PROXY

Added the corresponding --preroxy command line option. Sets a SOCKS
proxy to connect to _before_ connecting to a HTTP(S) proxy.

... the newly introduced CURLOPT_SOCKS_PROXY is special and should be
asked for specially. (Needs new code.)

Unified proxy type to a single variable in the config struct.

This was added as part of the SOCKS+HTTPS proxy merge but there's no
need to support this as we prefer to have the protocol specified as a
prefix instead.

... they're already frowned upon in our source code style guide, this
now enforces the rule harder.