Refactor api, DownloadImage is now DownloadAndUnpackImage and can specify
the prefered unpack method.
We should be now api stable for v0.x branch

Uncompressing with tar and --xattrs is too much depending on the system
configuration which is being run on. For example, it seems with certain
versions of gnutar it's not possible to extract cap bits, and bsdtar should be
used instead.

With this change we glob methods used by moby, containerd and umoci to unpack layers
and thus removing the tar dependency when unpacking docker image layers.

Version bump

Bump version again, we forgot last time :stuck_out_tongue:

Avoid exception if files .dockerinit / .dockerenv aren't present

Update README and bump version in main

Fix compilation issues wrt moby switch

enhancing output and coverage

main: version bump

bump version to 0.3.2