New: row.add() and rows.add() methods for the new API

- Two new methods for the new API to allow new data (rows) to be added
  to the table.

  - row.add() - Add a single row to the table. object, array, jQuery
    object or TR node can be passed in.

  - rows.add() - Add one or more rows to the table from a source array.
    An array or jQuery object must be passed in, containing objects,
    arrays, or TR nodes (or any combination thereof).

- Should be noted that this is iterated over all tables in the current
  API context, so care should be taken when adding a node to multiple
  tables, since it will be moved between them. Equally, when adding
  data, the original object reference is retained, so changing it in one
  table will change it in all!

- These two methods effectively replace fnAddData from the old API.
  fnAddData had a few issues with distingusihing a multiple row add and
  a single row add, since arrays could be used for both (indeed, it
  simply couldn't cope with something like using a single integer as
  reference for a data object, which can now be done in 1.10). The two
  new methods sidestep this problem by providing one method for multiple
  row add, and another for single row add - the developer needs to know
  that the plural has meaning here!