BA Weber

This PR includes the following changes:

• Support for multiple datasets and models
• Implementation of retraining (training in a specific order and loading pretrained weights)
• Reading result of EMADL2CPP change detection to decide if a model needs to be retrained
• Usage of pathlib (instead of os.path to follow PEP 428)
• Some code improvements (pylint)
• Removal of dangerous default arguments (e.g. lists)
• Application of isort
• Usage of lazy formatting in logging strings

Since the changes are based on some dependencies, the merge order is important:

graph TD;
  Datasets-->MNISTCalculator;
  emadl-maven-plugin-->MNISTCalculator;
  emadl-maven-plugin-->Datasets;
  maven-streamtest-->emadl-maven-plugin;
  CNNArch2X-->maven-streamtest;
  EMAM2Middleware-->maven-streamtest;
  EMADL2CPP-->maven-streamtest;
  CNNArch2X-->EMAM2Middleware;
  EmbeddedMontiArcDL-->EMADL2CPP;
  CNNArchLang-->EMADL2CPP;
  CNNArch2X-->EMADL2CPP;
  CNNArch2Gluon-->EMADL2CPP;
  CNNArch2X-->CNNArch2Gluon;