Added autosave in x seconds feature.

[pmjames29]

Hey, I implemented a feature for autosaving modified files in x seconds. Currently, it works by checking if there is no input for the specified amount of time in the configuration, and then it will save all modified buffers in the editor. For files that have been modified on the disk with changes in the editor, it will not autosave the new changes. There is a bug currently when inputting backspaces, as it does not reset the timer for the autosave and will autosave as if no changes are being made, even though there is user input. The session modified buffer functionality has some overlap with this, and once it is implemented it may be able to fix the problem. You may already be trying to implement this with the session modified buffer code, so you might want to discard or take what pieces you want from this, thanks.

[obiwanus]

Thanks for your PR.

We're pausing all PRs until the next release, we'll have a look after it's done.

I had a quick look, one thing I noticed - why do we need an additional timer? There's an auto-refresh timer already which should be sufficient.