Split IndexColumn#[]=

IndexColumn#[]= is deprecated. Use #add, #delete or #update instead.

    index_columns[record] = {
      :value   => value,
      :section => section,
    }
    # ->
    index_columns.add(record, value, :section => section)

    index_columns[record] = {
      :old_value => old_value,
      :section   => section,
    }
    # ->
    index_columns.delete(record, old_value, :section => section)

    index_columns[record] = {
      :old_value => old_value,
      :value     => new_value,
      :section   => section,
    }
    # ->
    index_columns.update(record, old_vlaue, new_value, :section => section)