For failed tests, show the full .exp and .out files

It only does this if there are failed tests, but XFAIL is not included in the
"failed tests".

.travis.scripts/debug-script.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+EXP=`echo $1 | sed 's/diff/exp/'`
+OUT=`echo $1 | sed 's/diff/out/'`
+
+echo "FILE $1"
+
+echo $EXP
+echo "======"
+cat $EXP
+echo "======"
+
+echo $OUT
+echo "======"
+cat $OUT
+echo "======"
+
+echo
+

.travis.yml

@@ -41,4 +41,4 @@ after_success:
 
 after_failure:
   - find . -name \*core\* -exec ./.travis.scripts/debug-core.sh {} \;
-
+  - find . -name \*diff -exec ./.travis.scripts/debug-script.sh {} \;