Keypress to test hardware in expServer

[k1o0]

Pressing a key could run a series of tests pre-experiment, e.g. display a stimulus, test inputs and output some audio through each speaker.

This may be difficult to implement as ChoiceWorld and Signals work slightly differently (although both use the have rig hardware object). Signals expDefs output to a different devices, thus we could have an expDef specific test that is run from mc?