Allow package installation from git repositories hosted anywhere

[khinsen]

Describe the request

Metacello supports loading packages from GitHub (documented) plus a few more undocumented sources (gitlab, gitlocal, ...). It should permit loading packages from any git repository hosted anywhere: other forges, and private git servers.Whatever git can clone from should be OK for Metacello as well.

Expected behavior

Metacello new
    baseline: 'MyPackage';
    gitRepository: '[email protected]:mypackage.git';
    load.

should be acceptable (or some variant).

Expected development cost

I don't know. I don't even understand why this doesn't work. I'd expect it to be easier to just pass on a repository reference to git, rather than take the information in a more restricted format and then construct the reference from that. I suspect there are good reasons, related to how Metacello and/or Iceberg work, but I have no idea what those reasons are and what it would take to work around them.