Shifted loadScript() function location

Moved it out of the IIFE so that it can be used on the global scope
Added page-specific function

Instead of checking for the nodes that exist on all the pages we visit,
why not check what page is it and then carry out the exact function that
we need?
Updated loadScript() function

Now you can either load a single link, or an array of links.
Updated bannerify() function

Added booleans which will trigger whether or not the function will add
in next/previous buttons and pager buttons.
Updated dropdownify() function

Now it is possible to wrap a <select> node with a parent node
(preferably a <span> node), and call the function on the said parent
node. The function will automatically transfer over the parent node's
classes and ID to the dropdown node when it is created. Useful when you
can't use data attributes on the <select> node itself.

If you're using a class to trigger the function, and you don't want this
class to be transferred over. then you can use the filterClass argument
to have the function filter it before transferring over.