Deprecate shell_cmd function and update system, dos, unix commands * NEWS: Announce deprecation of shell_cmd. * deprecated/shell_cmd.m: New file to hold documentation and warning for shell_cmd. * deprecated/module.mk: Add shell_cmd to build system. * mk_undocumented_list: Remove shell_cmd from undocumented list. * install.txi: Replace reference to shell_cmd with system. * dos.m, unix.m: Update docstrings and add %!test block. * toplev.cc (system): Update docstring and add %!test block.

--- a/scripts/deprecated/module.mk	Thu Dec 08 19:25:38 2011 -0500
+++ b/scripts/deprecated/module.mk	Thu Dec 08 17:25:30 2011 -0800
@@ -24,6 +24,7 @@
   deprecated/replot.m \
   deprecated/saveimage.m \
   deprecated/setstr.m \
+  deprecated/shell_cmd.m \
   deprecated/sphcat.m \
   deprecated/spvcat.m \
   deprecated/strerror.m \