bug fix: a possible bug already noticed for the evaluation of the Hamiltonian has been fixed.
description of the bug: the i,j element of the Hamiltonian was not *added* to the sparse matrix but *equated*,
this imply that in the same row (i) no other contribution to this column (j) existed already, possibly leading
to errors in the evaluation of the Hamiltonian sparse matrix in multi-band systems.
fix: the full_ed code just add to the 2dim array. for the lanc_ed code I implemented a check in the
sparse matrix insert element routine (sp_insert_element) so to add value to an already existing column or
create a new node in case no element with the same column j existed.
- the sp_init_matrix has been moved to ed_geth routine. it is important to delete the spH0 matrix while this is not needed anymore
to save memory space. A check is implemented in ed_geth to help degug.