Breaking changes

[nicl]

As more people use the library and things mature, we'll want to become more cautious to introduce breaking changes. SemVer is great, but it's not much use if we continue to release breaking changes at a high cadence.

My suggestion is at somepoint in the next quarter we commit to avoiding breaking changes, except for security fixes. I.e. if we were at v40 at the time, we would expect to sit on that major version for a while.

A consequence of this is that we might need to introduce new patterns where we want to significantly change how e.g. lambdas or EC2 deployments work rather than modify the existing patterns in breaking ways.

And eventually, if we want larger changes, we could consider releasing a 'v2' of the library - i.e. as a different package/import path. Hopefully that wouldn't be needed for a long time though.

This will mean more work for us (in supporting existing behaviour) but help teams access new features without the friction of fixing lots of breaking changes.

[nicl]

Closing as migrated to: #910.