dabba: remove obsolete/unused rpc_dummy_print().

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: refactor replies YAML output functions.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: refactor thread_settings_print function.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>