Now:
- <set_cheby_nosoc>= T sets SOCSCL=0 but uses coupled spin channels (e.g. for noncollinear calculations without SOC)
- <decouple_spins_cheby>= T assumes that spin channels can be decoupled (collinear, without SOC)

- NSIMPLEMIXFIRST>0 activates simple mixing for the first NSIMPLEMIXFIRST if IMIX>3
- SPINMIXQBOUND is the spin mixing threshold after which all angles are assumed to be converged and will be fixed

Bug fix: corrected calculation of spherical angles from the spin moment vectors for the cases theta=0 and pi

Changes involving read_angles:
-- wunfiles: sets theta, phi and fixdir in t_params, new override with fix_nonco_angles, broadcasts values
-- main1a, main1b, main1c, writekkrflex: replaced call to read_angles with assignment from t_params

Changes involving fix_nonco_angles:
-- wunfiles: used to override fixdir
-- rhovalnew: now uses fixdir to decide if the local frame has to be corrected, new angles always computed
-- main1c: decides on nonco_angle_out.dat, now always write information on new angles

Otherwise from 50x50x50 k mesh on the NofKs number exceeds the field width

force at least two iterations for LDA+U (otherwise initial step will stop if starting potential is converged)

- fix initialization of gfint
- implement QBOUND_LDAU to control how well LDAU potential should be converged