fix: Synchronous session load on startup (#28)

[k1rowashere]

Adds option to load session synchronously on startup to prevent flickering of the intro-screen.
(with readme changes to show how to make it fast)

Implements the solution shown in #28 (comment).

demo: (first run without option, second with)
Screencast from 2024-04-30 18-56-56.webm

[Shatur]

Thank you!
I tried it and it works just fine without any additional tweaking.
I think that we should make it a non-configurable default behavior.

[k1rowashere]

I think this should be labeled as a fix.

[Shatur]

Ah, sorry, I wanted to say that we don't need to vim.schedule at all 😄
I originally wrote this plugin long time ago and didn't have this knowledge back then, but there is a nice video from one of the Neovim main developers.
After looking at this code now, I think that we should just drop vim.schedule at all.

[k1rowashere]

I assumed there was a reason for the vim.schedule so I initially kept it lol.
I reverted everything and just removed vim.schedule from utils.load_session

[Shatur]

Thank you! Let me use this branch for a few days, maybe I will catch some issues.

[Shatur]

Works perfectly!