add ML interfaces

feedbackloop.learner_backup/src/main/java/de/tudresden/inf/st/eraser/feedbackloop.learner_backup/MachineLearningDecoder.java

+package de.tudresden.inf.st.eraser.feedbackloop.learner_backup;
+
+public class MachineLearningDecoder {
+}

feedbackloop.learner_backup/src/main/java/de/tudresden/inf/st/eraser/feedbackloop.learner_backup/MachineLearningEncoder.java

+package de.tudresden.inf.st.eraser.feedbackloop.learner_backup;
+
+public interface MachineLearningEncoder {
+}