Closes #811

Closes #762

Because the old OpenSSL link now redirects to their master documentation
(currently 1.1.0), which does not document the required actions for
OpenSSL <= 1.0.2.

Closes #727

Mention possible content-length mismatch with sum of bytes reported
by write callbacks when auto decoding is enabled.

See #785

Closes #786

As discussed in #785

Reported-by: mgendre
Closes #784

Even if deprecated, document it so that people will find it as old
scripts may still use it.

Bug: https://curl.haxx.se/mail/lib-2016-04/0126.html
Reported-by: Bru Rom

... although it is deprecated.

This also fixes PolarSSL session resume.

Prior to this change the TLS session information wasn't properly
saved and restored for PolarSSL and mbedTLS.

Bug: https://curl.haxx.se/mail/lib-2016-01/0070.html
Reported-by: Thomas Glanzmann

Bug: https://curl.haxx.se/mail/lib-2016-04/0095.html
Reported-by: Moti Avrahami

Fixes #779

Closes #716

Closes #686 for now.

Adding support for IRIs is a mouthful, but is probably interesting at
least for areas and countries where the use of such "URLs" are growing
popularity.

Closes #776

As of commit d9f3b365

... to make it easier to add lines in patches that won't just break all
other patches trying to add lines too.