adventure.yaml coverage test script -- not at all polished, but works

Closed username-removed-1096594 requested to merge traas/open-adventure:master into master

Just outputs a line for each location description, arbitrary message, or object description that isn't present in any of tests/*.chk, so we make sure we're covering the whole file.

I can add more categories, and generate an HTML report, and add other nice features, but this is the first version.