Closes gh-16028

Closes gh-16424

Closes gh-16348

Closes gh-16352

See gh-16421

Closes gh-16421

See gh-16418

Closes gh-16418

Remove a few items that are no longer necessary.

Update the eclipse setup files and contributing instructions for
compatibility with the latest Eclipse 2019-03 release. This commit
reverts the use the HTTPS in the `.setup` file namespace (since it
breaks the setup editor). The `xsi:schemaLocation` section still
uses HTTPS for actual XSD resolution.

See gh-16245

Closes gh-16345

Closes gh-16358

Closes gh-16338

In addition to upgrading to Jetty 9.4.15, this commit updates the
KeyStores used in embedded container testing to add to their entries
subject alternative name extensions for localhost and 127.0.0.1. As
of 9.4.16, Jetty requires the SAN extensions.

Closes gh-16188

Closes gh-16387

Previously, if the directory to which Tomcat would write a file upload did not exist
the upload attempt would fail and a 500 response would be returned to the client.
This could happen when, for example, Tomcat is using a temporary directory for file
uploads and tmpwatch has deleted the directory.

This commit configures Tomcat so that, during multipart request parsing, it will
automatically create the directory to which the parts will be written if it does not
already exist.

Closes gh-9616

Closes gh-16364

Closes gh-16363

Closes gh-16362

Closes gh-16361

See gh-16316

* gh-16318:
  Polish "Use HTTPS for external links wherever possible"
  Use HTTPS for external links wherever possible

See gh-16381

See gh-16318

* gh-16317:
  Polish "Use HTTPS for external links wherever possible"
  Use HTTPS for external links wherever possible

Closes gh-16317

See gh-16317

See gh-16317

See gh-16316

* gh-16316:
  Polish "Use HTTPS for external links wherever possible"
  Use HTTPS for external links wherever possible

Closes gh-16316

See gh-16316

See gh-16316

* gh-16313:
  Use HTTPS for external links from XML files where possible