API changes across minor versions considered harmful

[rueberger]

We have a project which was developed and tested against antspyx==0.3.2. As we are preparing the final proofs and repo for publication I have discovered to my horror that the 0.3.2 binary is no longer available on PyPI. Further to my horror, there has been a breaking change in the API - ants.core.ants_image.ANTsImage is no longer aliased to ants.ANTsImage. Needless to say this is less than ideal, and is why god invented __init__.py.

[cookpa]

Space limitations on pypi necessitated the removal of earlier versions.

Now that the wheels are much smaller, the lifespan of releases on pypi should be much longer.

The antsImage import change was unintentional and was fixed in #700, but hasn't made it into a release yet.