Improved support for sequences with unknown length thanks to @WohthaN

Fixed resizing with nested progressbars

Fixed output redirection with special ipython and jupyter notebook su…

…pport

Fixed Linux integer overflow bug with ETA

Bumped version for pypi

Fixed strange git undo

improved test coverage v3.9.1

Finished ETA widgets

modernized the package and improved python 3 support

added more widgets, dropped python 2.6 support and improved testing