Started working on horizontal scrolling
Merge branch 'horizontal' of https://github.com/massimoksi/MplusL-web into horizontal

* 'horizontal' of https://github.com/massimoksi/MplusL-web:
  Started working on horizontal scrolling
Adapted html and css code to support both the grid and the horizontal scrolling layout
Started working on javascript to respond to horizontal scrolling
Implemented logic to activate the link in the navigation menu related to the visible page
Renamed parallax.js into scroll.js
Implemented document resizing according to visible section
Minor changes
Added section centering when resizing the window
Fixed a typo
Modified style of hovered links in the navigation menu
Minor changes
Merge commit 'bb7b2ba85e77add9bd27b28a20d659595444f99d'