To remove Scan2data/user_input.py

[emilinecsa]

We should remove Scan2data/user_input.py
Scan2data/user_input.py is the older version of user_input_md.py. The md stands for metadata.

This avoids confusion. In addition, the less code we have, the easier the application is to maintain.

[js-kalsi]

Hey @emilinecsa, I have picked this card and created a PR: #21