modular/shell: Start reorganizing the shell material

Mostly split the examples out into their own directories with READMEs,
but there was a lot of editing to partially convert the long-form
notes into a condensed instructor.md targeted at instructors.  I've
gotten to the pipes section and run out of steam.  Erik may be taking
over the rest of the rewrite...

W. Trevor King: I dropped everything from the original 7ba5e9d except
for the modular/shell/exercises/hearing/README.md addition.  I also
merged in the history of the shell notes from
git://tremily.us/swc-modular-shell master so you can follow the
development of the README content.

diff --git a/README.md b/README.md
new file mode 100644 (file)
index 0000000..61d5fda
--- /dev/null
+++ b/README.md
@@ -0,0 +1,36 @@
+# Cochlear Implants
+
+A cochlear implant is a small electronic device that is surgically
+implanted in the inner ear to give deaf people a sense of
+hearing. More than a quarter of a million people have them, but there
+is still no widely-accepted benchmark to measure their effectiveness.
+In order to establish a baseline for such a benchmark, our supervisor
+got teenagers with CIs to listen to audio files on their computer and
+report:
+
+1.  the quietest sound they could hear
+2.  the lowest and highest tones they could hear
+3.  the narrowest range of frequencies they could discriminate
+
+To participate, subjects attended our laboratory and one of our lab
+techs played an audio sample, and recorded their data—when they first
+heard the sound, or first heard a difference in the sound.  Each set
+of test results were written out to a text file, one set per file.
+Each participant has a unique subject ID, and a made-up subject name.
+Each experiment has a unique experiment ID. The experiment has
+collected 351 files so far.
+
+The data is a bit of a mess! There are inconsistent file names, there
+are extraneous `NOTES` files that we'd like to get rid of, and the
+data is spread across many directories. We are going to use shell
+commands to get this data into shape. By the end we would like to:
+
+1.  Put all of the data into one directory called `alldata`
+
+2.  Have all of the data files in there, and ensure that every file
+    has a `.txt` extension
+
+3.  Get rid of the extraneous `NOTES` files
+
+If we can get through this example in the available time, we will move
+on to more advanced shell topics…