Added test to cover the case when cmdarg_purge erases or otherwise makes the cmdarg_cfg internals unusable, also changed the purge method to something much simpler

tests/test_clean_state.sh

@@ -1,5 +1,30 @@
 source $(dirname ${BASH_SOURCE})/../cmdarg.sh
 
+function shunittest_clean_state_usable()
+{
+    function parse1()
+    {
+	cmdarg 'a:' 'a' 'some arg'
+	cmdarg 'b' 'b' 'some arg'
+	cmdarg_parse "$@"
+    }
+
+    function parse2()
+    {
+	cmdarg_purge
+	cmdarg 'c:' 'c' 'some arg'
+	cmdarg 'd' 'd' 'some arg'
+	cmdarg_parse "$@"
+    }
+    parse1 -a 3 -b
+    parse2 -c 5 -d
+    [[ "${cmdarg_cfg['c']}" == "5" ]] || return 1
+    [[ "${cmdarg_cfg['d']}" == "true" ]] || return 1
+    [[ "${cmdarg_cfg['a']}" == "" ]] || return 1
+    [[ "${cmdarg_cfg['b']}" == "" ]] || return 1
+    return 0
+}
+
 function shunittest_clean_state()
 {
     # Tests that cmdarg_purge ensures an empty config state
@@ -55,4 +80,4 @@ function shunittest_clean_state_subshells()
 	cmdarg_dump
 	return 1
     fi
-}
+}