Implement snapping.

- Now using jQuery panelSnap plugin to drive navigation (replacing the previous smothScroll plugin)

- Major changes to CSS and JS

- Replacing JS functionality with pure CSS alternatives (section height control)

- Content layout change: 100px padding-top, 1-column gutter between nav and content and width reduced to 6 columns.
Merge branch 'master' of https://github.com/GilmarLira/thehexcode