Merge pull request #7 from stovocor/reuse

Do not start graphical programs during maven tests
remove oldInvalidated from QueryResult, use global on ReuseOracle, invalidate in ReuseTree#fetchSystemState
Builder for ReuseOracle, JavaDoc, method rename
Merge branch 'reuse' of github.com:LearnLib/learnlib into LearnLib-reuse

Conflicts:
	examples/src/main/java/de/learnlib/examples/example3/Example.java
	filters/reuse/src/main/java/de/learnlib/filters/reuse/ReuseOracle.java
	filters/reuse/src/main/java/de/learnlib/filters/reuse/tree/ReuseTree.java
	filters/reuse/src/test/java/de/learnlib/filters/reuse/test/LearningTest.java
	filters/reuse/src/test/java/de/learnlib/filters/reuse/test/QuiescenceTest.java
	filters/reuse/src/test/java/de/learnlib/filters/reuse/test/ReuseOracleTest.java