* Regexp improvements

* Added check for libxml in configure';
  * Added clixon_util_regexp utility function
* Yang state get improvements
  * Integrated state and config into same tree on retrieval, not separate trees
  * Added cli functions `cli_show_config_state()` and `cli_show_auto_state()` for showing combined config and state info.
  * Added integrated state in the main example: `interface/oper-state`.
  * Added performance tests for getting state, see [test/test_perf_state.sh].

util/clixon_util_insert.c

@@ -31,16 +31,8 @@
 
   ***** END LICENSE BLOCK *****
 
-See https://www.w3.org/TR/xpath/
-
- * Turn this on to get an xpath test program 
- * Usage: xpath [<xpath>] 
- * read xpath on first line and xml on rest of lines from input
- * Example compile:
- gcc -g -o xpath -I. -I../clixon ./clixon_xsl.c -lclixon -lcligen
- * Example run:
-echo "a\n<a><b/></a>" | xpath
-*/
+  * Utility for Inserting element in list
+  */
 
 #ifdef HAVE_CONFIG_H
 #include "clixon_config.h" /* generated by config & autoconf */