Add "git diff" script
It's a simple helper that depending on the arguments will either
use git-diff-files, git-diff-cache or git-diff-tree.
diff --git a/git-diff-script b/git-diff-script
new file mode 100755
index 0000000..d70e8b9
--- /dev/null
+++ b/git-diff-script
@@ -0,0 +1,16 @@
+#!/bin/sh
+rev=($(git-rev-parse --revs-only "$@"))
+flags=($(git-rev-parse --no-revs "$@"))
+case "${#rev[*]}" in
+0)
+ git-diff-files -p "$@";;
+1)
+ git-diff-cache -p "$@";;
+2)
+ begin=$(echo "${rev[1]}" | tr -d '^')
+ end="${rev[0]}"
+ git-diff-tree -p $flags $begin $end;;
+*)
+ echo "I don't understand"
+ exit 1;;
+esac
