Use `defcssfn` to define functions
Remove unused *output-style* var
Relax expand-1

This allows other non-hash-map types to appear in the document so long
as *selector-context* is nil.
Add prefix and vendor-prefix functions
Introduce support for at-keyframes

Keyframe generation includes automatic vendor prefixing.
Include garden.stylesheet.functions in user ns
Remove several broken garden.stylesheet tests
Implement print-method for CSSFunction
Fix project description
Set development version
Fix failing test

The original output is actually desired, but until logic in the
compiler can be written to handle this case I am expecting this as the
correct result.

The :compact flag may be removed in favor of a :pretty-print? flag.
Declare compile-css for use in keyframes