drop support for several package directories in one graph

e.g. you can't have packages in both node_modules and components

its simply a bad idea to use more than one in a single project so
why bother supporting it.
drop support for component
reduce fixtures
clean up comments
del fixture
basic support for aliases
allow unknown module types

don't know why I ever didn't allow it there isn't anything wrong
with it its just small possibility of being an accident
register aliases in the map

to save io
ensure output is unique
add a symlink to the example
ignores
simplify nodeish.hashSystem