make sure score is a number
Merge branch 'back-end-working' of github.com:lexloren/E99-Language-Learning into back-end-working
Fixes, improvements, optimizations; accommodation of unit-testing weirdness.
Merge remote-tracking branch 'origin/back-end-working' into back-end-working
Merge remote-tracking branch 'origin/master' into back-end-working