Since we've been quickly expanded the support for sha256, instead of making the regress "opt-in", make them "opt-out". Basically, only the regress that are reaching the network protocol code needs to be disabled as of now in sha256 mode (until we add support for git protocol v2).

Do the same for `got init' too obviously. Repositories created via `clone' are implicitly sha1 since we don't speak the v2 protocol (yet). ok stsp@

part of a larger diff that's ok stsp@

The counterpart of generating v3 bundles is to load them.

bundles v2 don't have a way to specify the object-format and so they can't work in sha256 mode; v3 adds a some "capabilities" so that it's possible to specify the object-format (and also other things that we aren't interested in actually.)

in a few cases, an array of SHA1_DIGEST_LENGTH has been converted to a struct got_object_id to simplify the handling.

suggested by stsp

This way core files will be left in the current directory instead that in the test one that is going to be immediately removed.

These were a bit hard to find. We set the id to 0xff[...] so they sort later, but the algo also needs to be set correctly.

extra (dumbiness) point for me to having chosen to use "41" instead of SHA1_DIGEST_STRING_LENGTH originally!