imposed spectra cannot be used together with telapy
when running multiple tomawac runs with teapy, a crash occurs when imposed spetcra are used. the issue is because NPSPE in the second run has a non-zeroe value (which it gets in read_coords_spectra, during the first call) In order to solve this, NPSPE needs to be reset to zero every time (for example in lecdon_tomawac)