Integrated the fix toward 1.521.

Based on further conversation with the Artifactory plugin developers, revisiting this extension point.

This is a breaking change, but this extension point was added very recently, and it's based on the input from Artifactory plugin, so there's not much point in keeping one that doesn't serve the intended use case.

"201 Created" response doesn't work well with a browser as the user agent.

The exception handler ended up adding almost all the headers again,
resulting in a lot of duplicate headers.

Most critically, stapler was adding "Content-Encoding" header twice,
breaking browsers.

Integrated the new version of remoting

Fire the "jenkins:apply" event from the apply button and listen to that to write back edits to <TEXTAREA>

Exposed the UI that sets the assigned label of matrix projects.
This deprecates the "Matrix tie parent" plugin.

Reimplemented a proper topological sort and generates a total order
comparison function.

FingerprintCleanupThread can now partially clean up a fingerprint record
by removing portions of it that's not referencing existing stuff.

[JENKINS-17713] [FIXED JENKINS-14362] These fixes were (mistakenly?) recorded for 1.518 rather than for trunk.

Integrated the new version of Stapler that fixes them.

properties that are applicable to the master node only and node properties
that can be applied to all nodes

[JENKINS-15380] noting. Ref. https://github.com/jenkinsci/jenkins/commit/029701ce3d109dc1a81991b09d23ba774a30fc2a

The plan of the record is that we start producing 1.6 class files and
see if people start complaining. If we hear from users, we'll re-visit
our decision, and if we don't, then we'll start using 1.6 features
everywhere in the code.

The slave launch thread is another background thread, and it should run
like a super-user

This can track items as they go through the queue.

This reverts commit 9fb2a025.

[FIXED JENKINS-16974] Unsafe to define a function in <script> without a generated name, as it could clash with functions defined in unrelated *.jelly that happen to included in the same page.

Noting the fix.