first implementation of BiCGSTAB
added QMRCGSTAB
seqAgg first version
bug fix in seqAgg
added inventory solver
use matrix interface in SeqAgg
removed zero checks (is faster)
added BiCGstab from Eigen
added bicgstab solver
added compressed row storage matrix
bicgstab inverse
added direct inversion method for BiCGStab solver
updated the README
added alternative for sparse LU invert
added make files for Linux builds and updated the README
moved matrix factory to solver
matrix-vector multiplication etc. + removed unused classes
added scale columns