Refactoring for better performance of large auto-cli specs

* Fixed: [very slow execution of load_set_file #288](https://github.com/clicon/clixon/issues/288)
* New `clixon-lib@2021-11-11.yang` revision
  * Modified option: RPC stats extended with YANG stats
* Modified `clixon-config@2021-11-11.yang` revision
  * Added option:
    * CLICON_PLUGIN_CALLBACK_CHECK
    * Enable to make plugin context check before and after all callbacks.
* Added statistics for YANG: number of objects and memory used
* Use the treeref no-copy option of CLIgen to reduce memory
* Refactored cli-generation/autocli-start code
* Refactored cligen glue functions to use cligen_eval directly (remove clicon_eval,clixon_cligen_eval)

test/lib.sh

@@ -270,6 +270,7 @@ fi
 # arg1: expected
 # arg2: errmsg[optional]
 # Assumes: $dir and $expect are set
+# see err1
 function err(){
   echo -e "\e[31m\nError in Test$testnr [$testname]:"
   if [ $# -gt 0 ]; then