pytesmo: v0.3.0

This release adds several new features, first among them Python 3 support. Changelog added calculation of pearson R confidence intervals based on fisher z transform ISMN reader can now get the data coverage for stations and networks ISMN interface can now be restricted to a list of networks added Python3 support moved grid functionality to pygeogrids package, pytesmo grids are deprecated and will be removed in future releases include triple collocation example and improve documentation see issue #2