Release Planning

[twalmsley]

We need to be aware that some of the GH issues are major changes that will affect the API and would mean the version needs updating to 3.x.x, and that this would mean that changes might still be needed for 2.x.x versions since not all users will be able to switch to the 3.x.x version straight away.

It could be worth adding a label to each issue to indicate its target version and trying to minimise the number of active release branches to reduce duplicated effort for supporting multiple versions. Obvious stuff, but worth mentioning.