Full clean Maven build has been failing with PermGen out of space on my system for
a while. Memory analysis indicates that there are excessive javac
instances lying around, so create fresh ones each time to avoid this.

With this change, I no longer need bigger heap size.

Technically this class was public, but no public plugin had ever refered
to it, and it's unlikely that anyone has referenced it, so this should
be safe.

fixed [JENKINS-15408]: Rotation of slave launch logs on Windows

Merge branch 'master' of https://github.com/jenkinsci/jenkins into ReopenableRotatingFileOutputStream-windows

[JENKINS-13202] 646154f1 refinement: resolveSymlink is documented to return null, not throw an exception, when called on a regular file.

The bug was actually already fixed and moreover this could cause that fireCompleted won't be called in case that cleanUp throws an exception, see commentes under https://github.com/jenkinsci/jenkins/commit/51f715162eba4dd1c4e081ec15c7ceb12e813ca5

Prevent to exception which causes that build will not be saved.

Conflicts:
	changelog.html

[JENKINS-15367] Fix Maven downstream resolution when declared as a specific version.

Document when EnvVars.get() function was added.

Set source/target level to 1.6 within the m2e profile.