Enable being dumped via pickle & similar

[jfhbrook]

Looks like some test/lint failures, but in the meantime: what the heck is motivating this change??

[LivInTheLookingGlass]

I'm running a bot to manage prediction markets on manifold.markets, and it would be great if I can load them into my database. The use case is for things like leaving a comment on market resolution as to why it was resolved that way

I implemented a hacky version of this in my code, and just now realized I could adapt this upstream so that someone else might not have that problem

[LivInTheLookingGlass]

There probably are better ways to implement the larger goal, but making this serializable was surprisingly simple. I'd already had to muck around with that to ensure logger objects and credentials don't get captured

[LivInTheLookingGlass]

Just wanted to bump in case this was forgotten about. The tests do pass now