Add Matrix preprocessor to list of datasets
Add MatrixPreprocessor
Change Preprocessor interface

Make preprocess return a DataModel
Many changes to YowModel

- Rename DB to table
- Add a few more support methods
- Move preprocessing code to class implementing Preprocessor
- Remove debugging code from main() method
Reflect changes to Preprocessor interface
Merge branch 'master' of github.com:ntnu-smartmedia/goldfish

# By Patrick Heia Romstad
# Via Patrick Heia Romstad
* 'master' of github.com:ntnu-smartmedia/goldfish:
  Multiple Linear Regression
  Merge

Conflicts:
	src/edu/ntnu/idi/goldfish/DataSet.java
	src/edu/ntnu/idi/goldfish/preprocessors/PreprocessorPuddis.java
	src/edu/ntnu/idi/goldfish/preprocessors/YowModel.java