* Experimental text syntax parser/loader

* Added new text syntax parsing and loading from CLI
  * Unified text output functions to `xml2txt` and moved to clixon_text_syntax.[ch]
    * The following are removed: `cli_xml2txt` and `xml2txt_cb`
  * Text output format changed:
    * Namespace/modulename added to top-level
  * See [Support performant load_config_file(...) for TEXT format](https://github.com/clicon/clixon/issues/324)

lib/src/clixon_xml_parse.h

@@ -58,6 +58,9 @@ struct clixon_xml_parse_yacc {
 };
 typedef struct clixon_xml_parse_yacc clixon_xml_yacc;
 
+/*
+ * Variables
+ */
 extern char *clixon_xml_parsetext;
 
 /*