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

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

Fixed trailing whitespace and numerous formatting glitches

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.

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.

In order to make the code style more uniform everywhere

Closes https://github.com/curl/curl/pull/1153

Since it now reads responses one byte a time, a loop could be removed
and it is no longer limited to get the whole response within 16K, it is
now instead only limited to 16K maximum header line lengths.

Now all options are in the new system.

Moved over to the new format

There's mostly likely no need to allow setting SSLv2/3 version for HTTPS
proxy. Those protocols are insecure by design and deprecated.

Closes #1142

Follow-up to 4f8b1774

Sorted the lists too.

... and include the new ones in the PDF and HTML generation targets