Make explain predictions work for new data again

[koenderks]

Started out as a bugfix for the Explain predictions table in mlPrediction, but turned into an optimisation where I removed the need to encode jaspML objects entirely! I verified that the predictions work with all models.

If you want to test yourself:

• Training dataset (Iris from Data Library): iris.csv
• All models trained on Iris dataset (classification predicts Species, regression predicts Sepal.Length): models.zip
• Prediction dataset with column names in different order than in training data: predictionData.csv

[vandenman]

looks good, one minor remark