Overhaul directory/file structure and root document

Moved the directories stored in the Assets directory to the root
level, and removed print.css and the grid system (grids to be
overhauled and re-added in the future), plus renamed:

* style.css to main.css
* master.js to main.js
* mathematical.css to base.css (to be reworked with grid includes
  and reset plus a more sane base type system)
actually remove files and include index.html changes