3.0.0.alpha.1

• No Mixins!
• Trim down to the core math, and a thin layer of api functions:
  • susy-span() to return a column-spanning width
  • susy-gutter() to return a gutter width
  • susy-slice() to return a slice of asymmetrical grid
• Simplify to four settings:
  • columns to define the grid columns
    as a list of comparable or unitless relative numbers
  • gutters to define the size of a gutter
    in units comparable to the columns,
    or a unitless relative number
  • spread to define the default spread of a span
    across adjacent gutters
  • container-spread to define the default spread of a container
    across side-edge gutters
• Shorthand syntax for overriding settings on-the-fly:
  • starting with a count, length, or column-list span
  • at $n, first, or last location on asymmetrical grids
  • narrow, wide, or wider for spread
  • of $n <spread> for available grid columns and container-spread