requested to merge 138-update-integrate-burgt-s-method-to-connectivity-box into development
Big update of Connectivity Box & associated/related boxes.
- added Burg/MVAR mode (in addition to Welch)
- externalized code of AutoRegressive coeffs from a Box to "spectrumTools.cpp". Added MVAR algorithm, + various optimizations.
- added boxes to help with managing (3D) connectivity matrices : 3D to 2D (with selection or averaging), 2D to Vector, Connectivity spectrum extraction (from given pair of channels)
- lots of bugfixes and improvements in connectivity box (timing management, bufferization issues are fixed, dimension labels...)
- added basic tests for MVAR and Welch modes