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/NEWS
+++ b/NEWS
@@ -154,9 +154,9 @@
 
       cut                is_duplicate_entry
       cor                polyderiv
-      corrcoef           studentize
-      __error_text__     sylvester_matrix
-      error_text
+      corrcoef           shell_cmd 
+      __error_text__     studentize
+      error_text         sylvester_matrix
 
 Summary of important user-visible changes for version 3.4.3:
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