Merge branch 'release/2.2.0' into develop
keep core style mixins out of global scope
make gutters with left margin/padding only to reduce output css
fix rounding errors in gutter (for higher grid widths specifically)
refactor documentation
provide an alternative, single mixin for basic grid setup -> fix problem with viewport dependent setups
refactor docs, new setup api
Update to v3.0.0
Merge branch 'release/3.0.0'