Merge branch 'namespaced' of git://tremily.us/swc-modular-shell-hearing into assembled

Avoid problems due to the shared history of swc-modular-shell,
swc-modular-shell-hello, and swc-modular-shell-hearing by restoring
the subject-level files and hello script removed in
swc-modular-shell-hearing:

  $ git checkout HEAD -- modular/shell/{README.md,cheat-sheet.md,instructor.md,exercises/hello/hello}

before commiting the merge.

Conflicts:
	modular/shell/cheat-sheet.md
	modular/shell/exercises/hello/hello