- Remove sortable.js(not used).
- Cleanup redirects, I couldn't properly look at it.
- Made main.js ECMA6 ready.
- Made event functions into a declaration to ensure compatibility with possible older browser version.
- Removed useless `=== true/false`.
- tempSrc uses declaration now.
JavaScript was checking if element clicked is exactly .nav-summary,
which isn't a problem when just clicking text inside it, but if we try
to click another element inside like <span>, it won't work, since now
this span is clicked, not .nav-summary.
Closes#1549
