Feature request: Create a unique subdirectory for the merged model

[vaahtio]

🚀 Feature Request

Summary

Currently the model output directory is specified in the merge configuration yaml file. While I can specify here a subfolder for the model, I believe it to be more intuitive and efficient to automatically create a unique subfolder per merge.

Motivation

This change helps to avoid accidental over-writes of the previously merged model.

[Optional] Implementation

add unique model name/identifier and create subfolder where the merged model is stored.