Add silly "git-whatchanged" script.

It's a one-liner, but it's useful as documentation if nothing else.

Makefile

@@ -19,7 +19,7 @@ AR=ar
 INSTALL=install
 
 SCRIPTS=git-apply-patch-script git-merge-one-file-script git-prune-script \
-	git-pull-script git-tag-script git-resolve-script
+	git-pull-script git-tag-script git-resolve-script git-whatchanged
 
 PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-read-tree git-commit-tree git-cat-file git-fsck-cache \

git-whatchanged

@@ -0,0 +1,2 @@
+#!/bin/sh
+git-rev-list HEAD | git-diff-tree --stdin -v -r "$@"