Advised and Enforced Management

[cstamas]

Originally, dependency management marked a "subject" as "managed", it was 0/1 true/false only. This PR now adds ability to mark management as "advised" (may be subjected to further management) or "enforced" (equivalent of previously "managed").

Changes:

• DependencyManager applies management as "enforced", if they come from root (ie. project POM), otherwise as "advice" (this latter applies to transitive managers only, as for example classic manager have no data from "deeper levels").
• ConflictManager backs out for enforced scope/optionality.
• This makes the "isInheritedDerived" hack in dependency manager not needed, as now management rule tells the modality of it (is enforced or just advised)

[gnodet]

Any idea about memory/perfs implications of the switch to Map?

[cstamas]

Did not perf measure it yet, but obviously will have some impact: none of code change affect long living objects, except the DefaultDependencyNode, where instead of byte we now have a Map. Will need to measure it.

All the rest of code changes is either very short living (DependencyManagement, PremanagedDependency) objects, or no effect like in case of DependencyManager instances...

[cstamas]

Superseded by #1815