add fullscreenenter and fullscreenexit detection (#273)
add fullscreenenter and fullscreenexit detection (#273)

msrresearch/jsPsych,jspsych/jsPsych,wolfgangwalther/jsPsych,jspsych/jsPsych,jspsych/jsPsych,wolfgangwalther/jsPsych,jspsych/jsPsych,jodeleeuw/jsPsych