Parallel Colt version 0.7.2 released

- Added new aggregate() method in 1D dense matrices.
- Added Modified Residual Norm Steepest Descent (MRNSD) solver.
- Added Conjugate Gradient for Least Squares (CGLS) solver.
- Added new solve() method in DoubleQRDecomposition and FloatQRDecomposition.
- Fixed few bugs in HyBR.
- Performance improvements in row-compressed sparse matrices.