Add functionality for per-mission event logging

[mcdelaney]

This adds functionality for per mission logging. Although I don't completely understand the Slmod config versioning system, I think that because I've only added one new option, and am testing for that variable to be nil, that everything here should be fully backwards compatible and not require any versioning increments.
Let me know if there's anything you'd like me to change.

[mrSkortch]

I will manually merge this in the changes I'm making for 7.6. Gonna slightly modify it though, but basis will be the same. Will close once integrated and working.

[mcdelaney]

What do you mean by manually merge? If you’d like me to make changes to the PR, I’d be perfectly happy to send an update.

[mcdelaney]

Did this make it into the last release?

[mrSkortch]

Not yet. Still slated for 7_6 due to changes needed for config among other things. Made a local branch as I merge changes in that I need to make for other files. General goal is to see if this last update is stable. If so, then merge to main. Eventually merge local changes into develop. Merge this PR. Then make edits as needed to that branch.

Also TBH got side tracked on other things the last few months. Lately I've gotten into working on this. So if that mood maintains I'll keep chipping away.

[mrSkortch]

Updated the whole config design. If you can make the changes for the 7.6 version then it will be ready to merge this. Sorry it took so long.

[mcdelaney]

Just getting back around to this... Thanks for the update. I'll try to update the PR in the next few days.