Tracking what to do before releasing 0.6.0.

There are already a lot of changes/improvements in this version. Since this will be a bunch of breaking changes, we should ensure all feasibly doable things that fall in this category get in as well.

The due date should be the time we should aim for of the release (not a hard deadline). Best to not have new issues/prs target this version about 5-7 days prior.