travis.yml: Testing all of core is too much code? It hung for 10m without any output.

travis.yml: Testing all of core is too much code? It hung for 10m without any output.

Maybe we could load-all then test core?
Also, maybe doing ``"math" test`` takes too long because we test all the subvocabs, so we should just test single vocabs at a time, non-recursively.