Possible BREAKING CHANGE fixes convert unit functions

Changes the default rem-calc, px-calc and em-calc from design-base to rem-base

Custom properties are coming

Always better:

• The css output is improved (no more useless first media-queries)
• The paddings and margins use calc() function now (goodbye explorer 8)
• Minor fixes

v1.15.0

Improves media-query and breakpoints use