0.17.5

Another smaller release. Fixes a regression from 0.17.4 and should drastically improve ETA and speed estimation thanks to great work by @afontenot in #539.

• Switch Estimator to use an exponential weighting (#539, thanks to @afontenot)
• Fix subtract with overflow when measuring terminal line length (#547, thanks to @foresterre)
• Add builder-like with_finish method to ProgressBarIter (#548, thanks to @matthewhchan)

On behalf of @chris-laplante and @djc, thanks to all contributors!