trackpy: Trackpy v0.4.1

Abstract

This is a minor release with some important fixes. Additionally, PIMS is nolonger a required dependency, which makes installation easier. See http://soft-matter.github.io/trackpy/v0.4/whatsnew.html for a full overview of the changes. Note: Full list of contributors: Aron Ahmadia, Thierry Bottaro, François Boulogne, Zoey S. Davidson, Rebecca Perry, Al Piszcz, Chaz Reid, Jan Schulz, Leonardo Uieda, and Devin Wieker