[Valladarex]

Fixes #315.

One commit.

• New: module Source/LK1/L1U/BDF_ID_LISTS.f03, subr READ_ID_LIST.
  • It reads an ID list from a field of the parent line through fields 2-9 of the continuations.
  • Items are single IDs or ranges "ID1 THRU ID2", in any mix and order; a range may run from one line to the next.
• Readers using it: SPC1, ASET1/OMIT1, USET1, PARTVEC1 and SPOINT (both passes; SPOINT now reads its continuations).
  • A record is still (ID1, ID2), as the old THRU branch wrote it, so the later processing is unchanged.
• PLOAD2: its range is the whole list, so IDs in fields 7-9 after it now stop with ERROR 1217.
• A wrong list stops instead of being cut short:
  • ERROR 1214: a THRU that does not follow an ID;
  • ERROR 1216: a list ending in THRU;
  • ERROR 1128: a range that goes down;
  • ERROR 1215, or the field reader's own error (1702 for a word): a field that is not an ID.

Test: MYSTRAN_Validation MystranSolver/MYSTRAN_Validation#34, spc1_thru_mixed.bdf, a CBAR chain whose SPC1 is "1 THRU 2, 5" with "7" on a continuation. Four checks:

• grids 5 and 7 do not move;
• the free spans match the clamped-beam hand values: P a^3 b^3 / (3 E I L^3) at grid 4, and P L^3 / (192 E I) at grid 6.

On dev all four fail, with grids 5 and 7 moving 1.8E-3 and 3.8E-3. With this PR all four pass.

Also checked, outside the suite:

• the same mixed lists on OMIT1 and ASET1 (SOL 103 eigenvalues), USET1 (the U1 table) and SPOINT (spring displacements) give the results of their IDs written one by one;
• the seven wrong lists each stop with their error and write no results.

Validation suite: with both PRs, 1 failure of 3,259 checks, the same one current dev has without them ("mitc4 thermal strain free rectangle cylinder", near-zero stresses in a strain-free thermal case). The 4 new checks pass.

[victorkemp]

SPOINT doesn't have continuation lines in MSC or Mystran. It could be an error but should not read them.

"Items are single IDs or ranges "ID1 THRU ID2", in any mix and order; a range may run from one line to the next." This isn't correct MSC or Mystran format for USET1, ASET1, OMIT1, SPOINT, or SPC1. THRU and a list a mutually exclusive within the same entry.