Add tests for the Python programs

Adjust 06-the-one/tf-06.py to avoid adding an extra blank line at the
end, so it will pass the tests.

test/test.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+function msg() {
+    echo $(date +%T) "$@"
+}
+
+failures=0
+total=0
+mydir=$(cd $(dirname $0); pwd)
+files=$(echo *.txt)
+for dir in ../[0-9][0-9]-* ; do
+    cd $dir
+    for file in $files ; do
+        exe=$(echo tf-[0-9][0-9].py)
+        msg testing $(basename $dir)/$exe with $file
+        python $exe ../$file | diff -b - $mydir/$file
+        result=$?
+        total=$((total+1))
+        if [ $result -ne 0 ]; then
+            failures=$(($failures+1))
+            msg FAILED!
+        else
+            msg passed.
+        fi
+    done
+    cd $mydir
+done
+
+msg $(date +%T) Ran $total tests with $failures failures.
+if [ $failures -ne 0 ]; then
+    msg FAILED!
+    exit $failures
+fi
+msg PASSED