* Add some tests to  current behaviour of getLog method

* getLog(maxLines) reads only last maxLines lines now

It should speed up and reduce memory consumption for some plugins (i.e.
Email-ext Plugin).
Also now this method could be used to get last lines of build output in efficient manner.

* Fix issues from code review

[FIXED JENKINS-39454] Do not consider pendings when deciding whether a schedule result should be new or existing, as we have already taken a snapshot of actions. (#2609)

[FIXED JENKINS-38487] - Jenkins startup must not fail in the case of ComputerListener failure (#2610)

Without this code Jenkinbs startup fails if EnvInject fails to find global property file on startup.

Javadoc says "Exceptions will be recorded to the listener. Note that throwing an exception doesn't put the computer offline." regarding the listener method exception, hence we should not block Jenkins startup

[JENKINS-39414] Stapler 1.247

[FIXED JENKINS-39404] Restore symmetry by adding removeAction and removeActions methods to Actionable

[JENKINS-39404] Clarify the lack of transaction support and consequent effect on concurrent operations

- cannot use a local variable as the optimization only applies while we have not found the action being added

- We cannot modify `replaceAction` to return the dirty flag, in fact most callers probably don't care... but if you do care, we now provide `addOrReplaceAction`
- Clarify the javadocs to reflect that these methods are not going to affect actions added by transient action factories

[JENKINS-39404] We cannot change these to return a boolean, but doesn't matter because they would always return `true`

I would need to use <A super Action> which would allow Object.class

[FIXED JENKINS-39404] Restore symmetry by adding removeAction and removeActions methods to Actionable

Update the detached version of Maven plugin to 2.14

We have to do it, because some extension points are being executed on slaves (e.g. https://github.com/jenkinsci/cygwin-process-killer-plugin/blob/master/src/main/java/com/synopsys/arc/jenkinsci/plugins/cygwinprocesskiller/CygwinProcessKiller.java - ProcessKiller EP gets propagated).

It's a follow-up to https://github.com/jenkinsci/jenkins/pull/2568

[JENKINS-39363,CID-1205051] - Prevent resource leak in hudson.XmlFile#readRaw() in the case of encoding issues. (#2518)

[JENKINS-39363,CID-1205051] - Prevent resource leak in hudson.XmlFile#readRaw() in the case of encoding issues.

[JENKINS-39232] Walk the DelegatingComputerLauncher instances when checking if JNLPComputerLauncher (#2602)

* [JENKINS-39232] Walk the DelegatingComputerLauncher instances when checking if JNLPComputerLauncher

* [JENKINS-39232] Add a system property to enable legacy plugins to continue to work until they get fixed

* [JENKINS-39232] Be more forgiving of plugins

* [JENKINS-39232] Yet more forgiveness of plugins but define the forward contract

* [JENKINS-39232] Provide diagnostics when this issue is encountered

- Since the failure of strict verification is an issue, we should log it as a warning always

* Add viewport meta tag

Enables better responsiveness on mobile devices

* fix: Use self-closing tag

* Remove minimum-scale for best accessibility

* [JENKINS-26940] Print message when installer isn't applicable

* [JENKINS-26940] Only print when none found, add test