Import/export NovelAI scenarios or stories

[tjohnman]

As the title says, it would be interesting to have a way to import (and export) NovelAI scenarios or stories. #90 implements import/export of SillyTavern format lorebooks, but perhaps it could be taken all the way for full inter-operability with those two platforms (in terms of world info/stories).

However, I think that would require a slight re-structuring of the code. For starters because I didn't find a way to pass information between modals, so a more flexible modal system would be useful for this and future features. I don't know the best way to approach this on the current code.