Major versions of modules
=========================

I.e. compatibility breaking versions.

In SLUL, these need a new name.
What naming convention should be used?

    pkg     - bad, cannot be co-installed with version 1.0 of "pkg"
    pkg2    - bad, gets confusing if "pkg" is a standard, like OAuth or HTML
    pkgv2   - bad, gets confusing if "PKGvX" is a standard, like IPv4
    pkg-2   - half-works, because "-" is also a common separator between
              name and version
    pkg-v2  - should work
    pkg_2   - works, but kind of non-standard
    pkg_v2  - works, but kind of non-standard
    pkg:2   - (where : is some symbol): the symbol could have a special
              meaning in other contexts, e.g. GNU/Linux distribution package
              managers.

---> pkg-2 seems like the best choice