switch to fwd.Reader
faster Skip() logic for readers
json does in-place string decoding
errors are typed
reading 'null' as anything else is now a strict type violation
offer Encode() for marshalers
*Writer is buffered
redefine standard interfaces for compactness and less generation
update readme
remove kind; replace w/ Type
Docs for msgp/msgp
Reference (forthcoming) wiki info
merge #28