Started updating doc
Fixed small typo in doc.
refer to matrix entries via rows
Fixed another small corner case in fmpz_xgcd.
Fixed dimension check in fmpz_mat_fread.
Did a TODO, used submul.
Allow transformation matrix to be requested along with HNF.
Neatened code and made minor improvements to fmpz_mat_hnf_classical.
Neatened hnf_minors code.
Changed ttest code for hnf_minors to compare against output from the classical algorithm
Neatened hnf_modular and made test compare with classical.
Added capability for hnf_pernet_stein to compute the hnf of completely arbitrary matrices and updated tests.
Changed message for the test for hnf_xgcd.
Added fmpz_hnf which chooses between classical and pernet-stein based on predetermined cutoff points