Very large commit for upcoming 4.4 release

Major New features

* New and updated search functions using xpath, api-path and instance-id
  * New search functions using api-path and instance_id:
    * C search functions: `clixon_find_instance_id()` and `clixon_find_api_path()`
  * Binary search optimization in lists for indexed leafs in all three formats.
    * This improves search performance to O(logN) which is drastical improvements for large lists.
  * You can also register explicit indexes for making binary search (not only list keys)
  * For more info, see docs at [paths](https://clixon-docs.readthedocs.io/en/latest/paths.html) and
[search](https://clixon-docs.readthedocs.io/en/latest/xml.html#searching-in-xml)

API changes on existing features (you may need to change your code)
* On failed validation of leafrefs, error message changed from: `No such leaf` to `No leaf <name> matching path <path>`.
* CLI Error message (clicon_rpc_generate_error()) changed when backend returns netconf error to be more descriptive:
  * Original: `Config error: Validate failed. Edit and try again or discard changes: Invalid argument`
  * New (example): `Netconf error: application operation-failed Identityref validation failed, undefined not derived from acl-base . Validate failed. Edit and try again or discard changes"

Minor changes

* Test framework
  * Added `-- -S <file>` command-line to main example to be able to return any state to main example.
  * Added `test/cicd` test scripts for running on a set of other hosts
* C-code restructuring
  * clixon_yang.c partitioned and moved code into clixon_yang_parse_lib.c and clixon_yang_module.c and move back some code from clixon_yang_type.c.
    * partly to reduce size, but most important to limit code that accesses internal yang structures, only clixon_yang.c does this now.

util/clixon_util_xpath.c

@@ -2,7 +2,7 @@
  *
   ***** BEGIN LICENSE BLOCK *****
  
-  Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren
+  Copyright (C) 2009-2020 Olof Hagsand
 
   This file is part of CLIXON.
 
@@ -58,7 +58,7 @@ See https://www.w3.org/TR/xpath/
 #include "clixon/clixon.h"
 
 /* Command line options to be passed to getopt(3) */
-#define XPATH_OPTS "hD:f:p:i:n:cy:Y:x"
+#define XPATH_OPTS "hD:f:p:i:n:cy:Y:"
 
 static int
 usage(char *argv0)
@@ -74,11 +74,10 @@ usage(char *argv0)
 	    "\t-c \t\tMap xpath to canonical form\n"
 	    "\t-y <filename> \tYang filename or dir (load all files)\n"
     	    "\t-Y <dir> \tYang dirs (can be several)\n"
-	    "\t-x \t\tXPath optimize\n"
 	    "and the following extra rules:\n"
 	    "\tif -f is not given, XML input is expected on stdin\n"
 	    "\tif -p is not given, <xpath> is expected as the first line on stdin\n"
-	    "This means that with no arguments, <xpath> and XML is expected on stadin.\n",
+	    "This means that with no arguments, <xpath> and XML is expected on stdin.\n",
 	    argv0
 	    );
     exit(0);
@@ -197,10 +196,6 @@ main(int    argc,
 	    if (clicon_option_add(h, "CLICON_YANG_DIR", optarg) < 0)
 		goto done;
 	    break;
-	case 'x': /* xpath optimize. Only if XPATH_LIST_OPTIMIZE is set */ 
-
-	    xpath_list_optimize_set(1);
-	    break;
 	default:
 	    usage(argv[0]);
 	    break;