Changed onkeypress to onkeydown event to listen

onkeypress event is not being generated in Chrome for arrow keys, with onkeydown everything is ok.
Changed onkeypress to onkeydown event to listen

onkeypress event is not being generated in Chrome for arrow keys, with onkeydown everything is ok.
Merge pull request #122 from j-martyn/patch-1

Navigation through files via arrowkeys wasn't working in Chrome