Note on using CTRL+J to jump back as well
Change info to refer to new location of setting
Lots of minor tweaks and code condensing

Text and comment improvements and additions in many places
Can now just use window.innerWidth/height, no need for ternary condition
Simplifying an if and ternary condition
contentCleanUp should happen on all files
Put the line swapping into 1 operation so an undo makes sense
Replace document.getElementById() with top.get() in many places
Add/remove vars to avoid global leaks/clear away old vars
Use break instead of escaping through var setting
Add != "/[NEW}" to if condition so we can open multiple new files
Remove old code re switch tabs to open file, this is handled by isOpen
if condition now
Condensing a lot of code on deleteFiles function
Condensed code a little on showMenu function re folderMenuItems