remove obselete cross-shell-tests helper

cross-shell-tests

@@ -1,15 +0,0 @@
-#!/bin/sh
-# Run urchin in a bunch of different shells,
-# including a shell that isn't quite POSIX-compatible (zsh)
-
-for shell in dash bash mksh ksh zsh; do
-  if which $shell > /dev/null 2> /dev/null; then
-    echo
-    echo Running urchin tests in $shell
-    $shell urchin -s $shell tests | tail -n 4
-  else
-    echo
-    echo Skipping $shell because it is not in the PATH
-  fi
-done
-echo