warninp could print the offending line, as well as its number
While fixing #2077, Berk proposed adding one-off code to write the final line of
ERROR 3 [file ddt2.prm, line 23]: Encountered a second block of parameters for dihedral type 9 for the same atoms, with either different parameters and/or the first block has multiple lines. This is not supported. line: CG2R51 CG2R51 CG321 CG321 9 0.000000 0.000000 3
This would be better done centrally, e.g. by passing the line to set_warning_line(), so that it is available and can be appended to messages for the convenience of users (and people helping with trouble-shooting on gmx-users).