Web app modularization

[lhelwerd]

Currently, the web application JavaScript is a big file with some separation of logic in functions, but still very complex and not modular. The CSS is similarly just one file for various purposes.

Primarily, the JavaScript should be more modularized to make it easier to reuse certain parts (such as the data) with proper scoping while also separating the logic in purpose, such as the various tabs, info subcells, scrolling behavior and so on.

[lhelwerd]

JavaScript modularization mostly handled by #19 although further improvements may be possible to make reloading the page with other data happen more cleanly (see #11)