When we edit a table with many many columns, use csv or dsv format is
not comfortable to work, what about let table plugin support a format
like (oddmuse longtable plug)[https://oddmuse.org/download/oddmuse-2.3.13/tables-long.pl] 

Instead of oddmuse style longtable, we can use YAML as table format:

    -
      a: 1
      b: 2
    -
      a: 3
      b: 4