Cleaning up some testing stuff.

- The Makefiles now run btest with "-f diag.log" so that diangnostics
  output will always be written into that file.

- Makefiles now hardcode path to btest to avoid picking up the wrong version
  if in PATH.

- The canonifier scripts now live in testing/scripts, and they are
  used from both btest/ and external/.

- There's a new diff-remove-uids scripts that removed connection UIDs
  for diffing. The external/* tests now use that by default.

- Timestamp removal now has its own script: diff-remove-timestamps.
  diff-canonifier calls that.

- All Makefile have a "brief" target that runs btest with -b.

- The higher-level directories have Makefile to call the subdirs.

testing/external/scripts/create-new-repo

@@ -34,8 +34,9 @@ done
 
 ln -s ../subdir-btest.cfg ./btest.cfg
 
-cp $cwd/`dirname $0`/files/test.skeleton tests
-cp $cwd/`dirname $0`/files/Makefile .
+cp $cwd/`dirname $0`/skel/test.skeleton tests
+cp $cwd/`dirname $0`/skel/Makefile .
+cp $cwd/`dirname $0`/skel/.gitignore .
 
 git add *