* For preparation for authorization RFC8341
* Plugins add clixon_plugin_init() and api struct for function pointers, eg:
```
static const struct clixon_plugin_api api = {
"example",
clixon_plugin_init,
...
}
clixon_plugin_api *clixon_plugin_init(clicon_handle h)
{
return (void*)&api;
}
```
* Moved specific plugin functions from apps/ to generic functions in lib/
* New generic plugin load function: clixon_plugins_load()
* Removed client-local netconf plugins netconf_plugin_callbacks()
* This was code used before generic YANG rpc calls
* Added username to clixon handle:
* clicon_username_get() / clicon_username_set()
* Added authentication plugin callback
* Removed some obscure plugin code that seem not to be used (please report if needed!)
* CLI parse hook
* CLICON_FIND_PLUGIN
* clicon_valcb()
* Removed username to rpc calls (added below)
