Add media query mixins
Remove some duplication of row/column resets for mobile
Add vertical margin to reset columns
Add "breakout" columns
Add a fix for IE 10 Snap Mode
Add fluid img styles
Add responsive visibility helpers
Add "breakout" columns
Add fluid img styles
Add first-column reset classes and better default variable creation.
Move grid generation out of the "shelves" mixin.

Add centered column helpers.
Reorder declarations so tablet and mobile centered columns work
By default breakout and centered columns will not be included
Add full column helper
Add full column helpers to breakpoints
Add missing .hidden-desktop helper
Add $first argument to column mixin
Add more support for Sass only usage
Some simplificaiton and refactoring
Simplify generated grid with @extend