3.0

• BREAKING: All pseudo-elements (box-sizing, cleafix) use proper :: syntax.
• BREAKING: Nested items in the $z-index list start with 1 rather than 2,
  so that main, nav item dropdown, overlay
  will generate indexes of 1, 2 1 2, 3 respectively.
  This matches more closely the way nested z-indexes work in the browser.
• BREAKING: Remove $inherit option from box-sizing
  (because it's a bad idea to inherit box properties).
  You can still replicate the behavior by setting box-sizing on the root,
  and passing inherit as an argument to the mixin.
• BREAKING: Remove micro-clearfix in favor of clearfix alias.
  The only other reliable clearfix is overflow: hidden -
  and we don't need a mixin for that.
• BREAKING: Remove $accoutrement-query-context and _apply-query()
  for lack of use-cases.
• BREAKING: Rename $_ACCOUTREMENT-ASPECT-RATIOS
  to make it private, and signify that it remains constant.
• BREAKING: Remove automatic browser-ems conversion,
  in favor of explicit breakpoint values/units.
  For unit-conversion and more helpful size-utilities,
  see Accoutrement-Scale.
  Also remove $_BROWSER-DEFAULT-FONT-SIZE, since it's no longer needed.
• BREAKING: rem values are treated like em values
  when removing media-query overlap.
• BREAKING: Remove stretch mixins, as an over-specific use-case.
• NEW: Add a single position mixin using the common TRBL syntax
  to provide a shortcut for positioning properties
  (top, right, bottom, left, and position).