[FIXED JENKINS-33453] Improve logging and error message when JNLP is already in use

[JENKINS-31847] CLI command clear-queue extracted from core to CLI

Remove mention of http.proxyHost property

Issue #2060

[FIXED JENKINS-21484]

Don't require ancient .NET 2.0 runtime. .NET 4.0 can host this
executable, too.

See https://github.com/kohsuke/winsw#net-runtime-40

[JENKINS-32684] Improved test coverage of CLI command 'console'

[JENKINS-32978] updated windows-package-checker to 1.2 to avoid compile time warnings

Fix typos in Swedish translation

JENKINS-32978

[JENKINS-33467] Do not store duplicate Cause’s

Use getInstance() in place of getInstanceOrNull() for execution paths that cannot have a null

The `@Initializer` and `@Terminator` annotated methods are only executed where `Jenkins.getInstance()!=null`

Fix Jenkins.getInstance() to make life easier for plugin authors

Revert JENKINS-32190 fix

[FIXED JENKINS-33425] Refactored the cleanUp() method to log progress and push for completion

Revert "[JENKINS-32190] Make UsageStatistics#isDue check Jenkins init level before generating stats."

This reverts commit d8a13ac0.

I noticed a strange drop in usage statistics from the mid Jan 2016,
which corresponds to the time this change was released in the wild,
and further drop when LTS 1.642.2 is released with this change at
the end of Feb.

I spent some time trying to determine how this might cause instances
to stop sending data, but I couldn't come up with any. I left those
notes in JENKINS-32190. There was some strange behaviours, but none
explains what this is.

So I'd like to back out this change and see if that makes any impact
on the stats collection. If it backs up, then we know empirically
this change is to blame, so that would justify spending further
effort or come up with a fix from a different angle.

[JENKINS-33414] Ensure that the tests do not leave the JVM marker flag set

[FIXED JENKINS-26580] Activate JNLP3 support