* previously the default gf_struct_solver had keys up / down,
inconsistent with the default behavior after analyse_block_structure was
run: up_0 / down_0. Now the default solver structure always has the _0
in the key.
* old behavior resulted in error when analyse_block_structure was called
twice
* fixed analyse block structure tests with new changes
* to correctly use analyse_block_structure use now
extract_G_loc(transform_to_solver_blocks=False)
* changed density_matrix function to use directly extract_G_loc() if
using_gf is selected.
* print deprecation warning in density_matrix, same can be achieved via
extract_G_loc and [G.density() for G in Gloc]
* new function density_matrix_using_point_integration()
* enforce in analyse block structure that input dm or G is list with
length of n_corr_shells
* correct doc string for how include_shells are given
* fixed other tests accordingly
* fixed small bug in initial block structure regarding length of lists
* typos and subbed check in spin polarized calculations for quantum espresso with a warning when computing the deltaN
* fixed typos in comments
* removed legacy mode maintaining only compatibility layer and switched to old (<3.10) python syntax
* added target density output in mu finder for brent and newton, refactored tunit test for DC, changed some comments
