[dlopezaldama]

Title: Fixes #378: GASPR missing light-particle production (MT875-891, prompt break-up, LR=1 levels, MF6/MT18, MF6/MT5)

Base branch: develop (rebased on NJOY2016.80, 51b1661).

What is fixed

1. (n,2n) given only by levels. MT875-891 are used when MT16 is absent (JEFF-4.0 Be-9: helium production
   at 14 MeV 0.0097 b instead of 0.986 b). (The recoil could contribute to gas production for light elements)
2. Particle-unstable residuals. NJOY2016 breaks up only Be-8; the other prompt-unstable light residuals are
   now broken up in the same way (B-9 → p+2α, He-5 → n+α, Li-5 → p+α, H-4 → t+n, Li-4 → p+He-3, Be-6 → 2p+α,
   B-7 → 3p+α). β-delayed decays (Li-8, B-8, Li-9) are not included. (This is an optional input for the IAEA/NDS version)
3. MT51-91 with LR=1. The light particles given in the File 6 subsections of these levels are counted (they were
   ignored), without counting a particle twice.
4. MF6/MT18. Light charged particles given in File 6 of the total fission (unusual evaluations) are counted, with
   a message; MT19-21 and 38 are partials of MT18 and are not used.
5. MF6/MT5. All the product yields of the same ZAP are summed on the union grid of the yields (the last one
   was kept); the charge and nucleon balance of the products is checked, with a message when they are not balanced.
   The unstable residuals of MT5 are listed but not decayed, as in NJOY2016.
6. terpa pointers are reset for each table; the storage for File 6 yields is allocatable (5000 → 100000 words,
   with a check), and the TAB1 length of the yields is taken from the record actually read.

Tests

• Rebased on develop (2016.80, 51b1661); replaces the earlier 2016.78-based commit of this branch.
• No new input option: the GASPR input is unchanged.
• LANL test suite: 87/87 pass with the existing reference tapes (no tape changes).

Release notes entry

Proposed text for the next release section of ReleaseNotes.md (not added to the file in this branch, to avoid conflicts between the open PRs):

• GASPR now uses MT875-891 when MT16 is absent, breaks up all prompt-unstable light residuals (not only Be-8), counts the light particles of MT51-91 levels with LR=1 given in File 6 and those of MF6/MT18, and sums all MF6/MT5 product yields of the same particle (issue gaspr issues #378).

[dlopezaldama]

Compared with the IAEA-NDS version, the IAEA-NDS version (28Oct26) introduces new input options: idec & mt5opt