Text progressbar library for python.

This library provides a text mode progressbar. This is tipically used
to display the progress of a long running operation, providing a
visual clue that processing is underway.

The ProgressBar class manages the progress, and the format of the line
is given by a number of widgets. A widget is an object that may
display diferently depending on the state of the progress. There are
three types of widget:
- a string, which always shows itself;
- a ProgressBarWidget, which may return a diferent value every time
it's update method is called; and
- a ProgressBarWidgetHFill, which is like ProgressBarWidget, except it
expands to fill the remaining width of the line.

Copyright: (c) 2005, Nilton Volpato
