Method to limit or ignore device schemas retrieved by netconf monitoring

[olofhagsand]

RFC 6022 NETCONF monitoring ietf-netconf-monitoring.yang defines a schema list that is the primary way in the clixon controller to get the modules to retrieve via the get-schema RPC, or via the local file cache under the "mounts" dir.
A method is requested to ignore or limit the schema list obtained in this way.
This can be useful for devices that may announce erroneous YANGs, or YANGs that are not in fact used.

1. One way is to introduce an ignore boolean config value in device or device-profile configuration. All Yangs are instead explicitly declared via the module-set configuration option.
2. Another method would be to constrain the YANG list obtained from the device by filtering some modules. This could be done with a negative module-set configuration option, ie, introduce a flag to module-set that instead of adding a YANG, removes a YANG from the list.