Feature: add the output of E_KS(sigma->0)

[Chentao168]

1. Add the output of E_KS(sigma->0), which is the same as energy(sigma->0) in the VASP.
   
   
   Here, I calculate E_KS(sig->0) = (this->f_en.etot - this->f_en.demet/(2+n_order)) .
   I find n_order = std::max(0, Occupy::gaussian_type).
   The following pictures are the related codes from VASP:
   
   
2. Rename E_demet to E_entropy(-TS).
3. Change setw(12) to setw(16) for allowing to show the E_KS(sigma->0) and E_entropy(-TS).

[wenfei-li]

how does the content of the pr relate to the title? I only saw change in E_entropy not E_KS(sig->0)

[hongriTianqi]

Add necessary explanation for your pr