0.3.0 Release Candidate 4

This contains bugfixes and necessary improvements for the final 0.3 release. 0.3 is still open for bugfixes. We have branched, relegating the release-0.3 branch for bugfixes and improvements for the 0.3.X series, and opening master for new breaking features and general development. This release candidate is expected to be promoted to the final release barring any major issues cropping up in the coming days.