New `grouping-treeref` option added to clixon-autocli.yang
Default is disabled, set to true to generate smaller memory footprint of clixon_cl
Add prefix "mtpoint:" to cli api-paths to identify change of yang schemas
* New automatic edit-mode design
* Control which modes to use with `edit-mode-default`
* Default is create edit-mode for all
* New edit-mode tree: @datamodelmode
* First version of clixon-autocli.yang semantics
* Default rules for module exclusion, list-keywords, completion, treeref-state
* Specialized rules for compress and exclusion of modules
* See [autocli documentation](https://clixon-docs.readthedocs.io/en/latest/cli.html#autocli)
* Obsoleted and moved autocli config options from clixon-config.yang to clixon-autocli.yang as follows:
* `CLICON_CLI_GENMODEL`, use: `autocli/module-default=false` instead
* Removed `clicon_cli_genmodel()`
* `CLICON_CLI_GENMODEL_TYPE`, use `autocli/list-keyword-default` and compress rules instead)
* Removed `clicon_cli_genmodel_type()`
* `CLICON_CLI_GENMODEL_COMPLETION`, use `autocli/completion-default` instead
* Removed `clicon_cli_genmodel_completion()`
* `CLICON_CLI_AUTOCLI_EXCLUDE`, use `autocli/rule/operation=exclude` instead
* `CLICON_CLI_MODEL_TREENAME`, use constant `AUTOCLI_TREENAME` instead
* Removed `clicon_cli_model_treename()`
* New YANG functions: yang_single_child_type, yang_find_namespace_by_prefix, yang_str2key
* Changed return values of yang_find_prefix_by_namespace
* Merged `cli_cli2xml()` into `cli2xml()`
