Updated Table Mode Public API

- Added tablemode#RowCount(line). Returns the total number of rows in a
  table given a line (row).
- Added tablemode#ColumnCount(line). Returns the total number of columns
  in a line (row).
- Added tablemode#RowNr(line). Returns the row number on given line.
- Added tablemode#ColumnNr(line). Returns the column on given line.
Releasing v2.3.0

- Refactored realignment logic.
- Generating borders by hand rather than relying on
  tabular formatting since that puts restrictions on the borders
  (padding). With the new scheme, I am able to generate good looking
  tables with neat borders like they should be, without padding.
- Updated doc/table-mode.txt