updated license
BF: exception when no correct in accuracy()
RF: got rid of mixedCase except for PsychoPy's leftovers

also:
ENH: exp auto-infers instructions from docstring
ENH: exp defaults to Left Shift + Esc for exit
ENH: last_keypress adjusted accordingly
ENH: wait_for_response works better with autorun
DEMOS: minimal demo added
TESTS: basic exp unittest added