This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
My discourse instance will be making regular automated public backups
of specific categories. It's preferred to be able to directly control
the path and filename of the output, rather than letting discourse
choose for me. This was already mostly supported, a filename parameter
just needed to be passed through the cli app.