NJOY2016.75

[whaeck]

This update fixes the following issues:

• Corrected a typo in the gateff subroutine in thermr (changed 1220 into 1200, see issue thermr typo in effective temperature values #76)

In addition, this update made added the following features and changes:

• A small change to the NXS array for continuous energy and photonuclear ACE files (iopt = 1 and 5): in both cases, the isomeric state S, atom number Z and mass number A are now stored in NXS(9), NXS(10) and NXS(11) respectively.
• A new input option for acer was introduced for setting the zaid identifier of the continuous energy and photonuclear ACE files (iopt = 1 and 5):
  • use za in the zaid regardless of the metastable state of the nuclide (default, this is how NJOY has always worked)
  • use the metastable zaid rules (MCNP 6.3 or lower) in which we use za for ground state nuclides and use za + 300 + s * 100 for metastable nuclides (Am242 and Am242m are exceptions to this rule, for these we use 95642 and 95242 respectively)