dev(lp): adding mps_reader,
 working on mps reader and general solver, debugging stage_one

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): stage_one, improving the mps reader, both stages seem working, passing up with walgrind

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): working on a pretty printer, small samples are passing, and pretty_printer works, implemented scaling

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): debugging precision, speeding up by sorting columns

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): fixing bugs in removing redundand rows, refactoring lp_revised_solver

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): solving correctly acc-tight5.mps, handling correctly redundant rows,  introducing sparse_vector and using it in the lower eta class - speeding up 3 times, , making zero() and one() of double inline, switching to static_matrix in m_A of lp_revised_solver

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : improving static_matrix, introducing col_struct, suhl_kernel_matrix makes sense,  more tests pass with suhl method

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : solving bigger lps with suhl method, reimplementing suhl method on sparse_matrix, improvoing work with lower_triangle_eta_matrix,  singletons seems working on sparse_matrix, simple factorization tests pass

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): solving smaller lps works again, getting back to the speed of 36 on acc-tight5.mps, suhl factorization of the whole matrix works

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : cleaning up sparse_matrix and fixing a bug in pivot choosing, avoiding duplicating the permutation in Q_R_calculator, using the simplifying suhl scheme

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>

save(lp) : reid factorization works, but there is numerical instability

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : adding more tests, fixing a bug in the preprocessor, setting a limit on the number of iterations of the core solver, adding argument_parser

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : refactoring lp_core_solver, fixing the parser and adding to the test driver an option to search for min

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp): avoiding using explicit low bound in lp_core_solver,  low upper bound at zeros seem working, the new calculation of reduced costs working

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : fixing a bug with fixed variables, harris double pass works

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : moving towards real steep edge strategy

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : switching to calculating the pivot row when getting the reduced costs, approximated column norms calculation works: solving acc-tight5.mps for 12 secs

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : improving debugging

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) : speeding up by creating an one_elem_on_diagonal_matrix instead of one_off_diagonal when possible

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>
save(lp) :  speeding up by limiting the factorization tail growth

Signed-off-by: Lev Nachmanson <levnach@microsoft.com>