Properly implement fluent interface in all writers.

Signed-off-by: Benoît Burnichon <bburnichon@gmail.com>
Merge pull request #88 from bburnichon/ticket_87_writer_fluent_interface

Add proper writer fluent interface tests
Nested itemconverter for recursive arrays including documentation and tests. Fixes #77 #94
Merge pull request #95 from gries/nested_item_converter_fixed

Nested array item converter
Provide option for setting redraw frequency. Also fix some non-declared class vars.