add support for windows path and session file

[4542elgh]

This is an attempt to fix Windows support for HOME environmental variables, (Windows should be using %UserProfile%). And allow session file to save successfully (Windows does not allow colon in filename and throwing an error in nvim)

[RhydianJenkins]

It's a good point about breaking compatibility. I'd be fond of having this cleaner approach but it's ultimately up to @jackMort over whether or not it's worth breaking compatibiltiy.

I can't see chat sessions as something so sacred that we can't clear them for this update. And we can always manually rename the session files if we REALLY wanted our old sessions back.