Could not find how to perform per-thread initialization e.g. for sqlite
In sqlite3's `MULTITHREAD` mode, one has to use a separate database connection for each thread.

I've gone through the jester and httpbeast source, but could not find where / how to perform per-thread init, for example to open a sqlite3 connection for each thread.

Unless I have misunderstood, I need a `{ .threadVar. }` db connection variable, but then have each thread init that separately. I don't see any places where I could easily hook this up, but I would love to be corrected!

(alternatively, one could opt to open the sqlite3 database in `SERIALIZED` mode to share the same connection option over threads, but the nim sqlite3 wrapper does not yet support the pre-requisite function calls (I might try to PR this at some point). Read more about sqlite3 threading modes here: https://www.sqlite.org/threadsafe.html

The default mode depends on sqlite3 compilation options. Here on my dev mac, it was compiled with `SQLITE_CONFIG_THREADSAFE=2`, which means a default of `MULTITHREAD` and not `SERIALIZED`. I would have to configure at runtime with either `sqlite3_config()` or preferably `sqlite3_open_v2()`)
