Updated to current latest stable version of jshint

I updated jshint to newest stable version. It finally correctly addresses #4175 and finds some additional issues with the code which I addressed. It found some missing "use strict" which I added when I thought they should be, or added an ignore switch otherwise.

ES5 option is now set per default, so I disabled it. [Reference](http://jslinterrors.com/es5-option-is-now-set-per-default/).