Make the code reproducible

[UlysseDurand]

The goal is to make the code reproducible and a little bit cleaner:

• All the ../dreamdiffusion were replaced by ./ so the git folder can change name
• A .gitignore was added
• The README was changed a little, those are suggestions and I would understand if this is too much.
• Some code was changed so errors in execution no longer exist (quite often, an absolute path was given)
• The env.yaml was changed to work today (new versions of pip made the old one not usable), the numpy version was specified to make it work (newer versions don't accept some syntax)

Thank you for reading this, I would appreciate discussion if you want to.
Best regards