Class structure just got better!

Many improvements here and an important milestone for going on with the project.

Main features

New LinearOp class as base class for Matrix/Operator class types
DataContainer renamed to Matrix, meant to hold raw arrays of data
- Added multiple matrix multiplication methods for better performance
- Partial reshape of the class with many non-member functions added
- Revisited many methods to make them make use of move semantics
New Operator class, meant to apply a transformation to a Matrix
Test suites now also provide performance calibration tools
General improvement and bug fixes