add dependency to check-args-impl@0.0.4
use more recent check-args-impl
override Signature.validate() and make Signature.with() an alias for it
override Signature.accept() and make Signature.after() an alias for it

- don't use Signature.on() because it cannot be made standalone function (reserved word in coffeescript)
replace on() with accept()/after() and make it accept only run() which returns the Signature object

-> call chain is now:
 after([pattern]).run(-> something...).after([other pattern]).run(-> something else)...
if arguments are given beforehand, override check to return same thing as normally
add convenience methods asMethod() and asConstructor() to be used for classes

These can be used for classes:
class X
  constructor: after(String).run((x)-> @foo = x).after(Number).run((x)-> @bar = x).asConstructor()
  foobar: after(String).run((x)-> @foo = x).after(Number).run((x)-> @bar = x).asMethod()
fix error with accept() when using arguments first approach
fix exports and imports
fix tests and add some new
build
bump up the patch number