Fixed demos link
set! support in cell macro
remove set! from specials, CLJS-571 protection. closes #5.

- cleaned up specials ns a bit
- removed %& use from specials, test namespaces
reformat license
bump version; remove done! from Cell type & api
remove cfn and defcfn macros
dox
remove unneeded convenience functions
remove self-referential code; repurpose ~ form; implement ~@ form
implement cell and cell= macros