Make a copy of the task evaluator for lazy evaluation.
Rename TaskEvaluator to EagerTaskEvaluator.
Move all evaluation classes to evaluation package.
Initial version of lazy evaluation.
Mostly working lazy task evaluation.
Merge branch 'master' into lazy-choice

Conflicts:
	org.metaborg.runtime.task/src/main/java/org/metaborg/runtime/task/TaskEngine.java
	org.metaborg.runtime.task/src/main/java/org/metaborg/runtime/task/TaskManager.java
	org.metaborg.runtime.task/src/main/java/org/metaborg/runtime/task/evaluation/EagerTaskEvaluator.java
Merge branch 'master' into lazy-choice
Merge branch 'lazy-choice'. Lazy task evaluator is disabled for now, the old eager evaluated is used.