codeAssist now set along with other settings

Also applied to checkbox so not always starting as checked, obeys user
settings
codeAssist set from settings, fixes to updating

codeAssist is now set along with other settings in index.php
solarized and xq-light should have lighter active lines too
If codeAssist isn't the same as out session setting, set it to the
updated setting and toggle the switch
Adjusts to CSS stylesheet targeting. New CSS file meant it's now
position 4 in the array and child item 4 where we'll find the content
style
I also changed background to background-color on the activeLine style
Updates to match main JS file
Style tweaks & lint obeys codeAssist setting

solarized and xq-light themes should have lighter active line
foldOff should be a white block with very low alpha, so it looks good on
themes with a light gutter
We should only JS lint if we have codeAssist on (and it's a JS file)