Add "all" subcommand to moromi

Using the standard build command without argcomplete available can be tedious. To help fix this, the all subcommand builds the complete configuration. Any internal dependencies are automatically detected and combined with the ordering of the keys in the config to decide the final order of the builds.

To support order hinting, the config parser now outputs an OrderedDict. There are also some updates to the description strings of the moromi argparser.