Don't require the full target filename with link, specifying a
directory should be enough.

link command should be smart enough to use absolute paths were
appropriate.

link command: support globs to create multiple links.

Should be support some form of else?
    sys:linux {
        ...
    } else {
        ...
    }

Support describing tags that are offered as choice.
    choice Dev "Development bundle"
    choice VM "When running on a VM"
However, we also need to be able to describe variables. Maybe call it "doc":
    doc @@hostname@@ Hostname to set for this machine
    doc Dev Development bundle

Support tags that are set by default, but can be negated:
    defaults mysql
Mysql will be installed by default, unless:
    wsconfig file apply -mysql

"dpkg one two" - currently, if "one" fails, "two" will never run, even if
execution is continued. Use generators to change that behavior.

Support running code only upon success of another command?
    Wine {
      dpkg wine (
          # runs only if wine was successfully installed.
          install_wine_apps
      )
    }

Allow simple communication between commands:
    # downloads to temp dir
    download http://....
    # runs the file just downloaded
    exec


Improve output formatting during runtime (i.e. the =====> syntax).
