Qbank output should go to a common output directory

[hollasch]

Here I am engaging in one of my biggest pet peeves: intermingling build output with source. Currently, the qbank project directs generated tests to the /qbank/out directory. This should instead go into something like /out/qbank. Keep generated output isolated to a single simple output directory. If a developer clobbers the /out directory, they should be left with nothing but source-controlled files.