introduce Row class
move join row to Row.render
move types to row
adjust_column_width rewrite cols
provide row index
move row type to row
remove table._row_types
extract parse_row
save
move calculate lens from merge to add
add column class
save
_row_type property
use row_type property
move norm to row
use Column
start extract is_column_separator
introduce Column sublasses
move row_type detection into constructor
use sublasses of column