incomplete input now results in an error when parsing json or jsx
internal form

streaming decoding is now only available when forced with the
`stream` option and no longer returns until forced to via the
token `end_stream`. this api is still subject to being replaced
with an even more explicit streaming mode
update README to reflect streaming changes
update README for veetwo changes
remove deprecated option flags handling
fix bad utf8 encodings by default (convert to u+FFFD)

this (temporarily, i hope) removes the fast path for handling
strings internally without escaping or replacing bad utf8
comments allowed by default. pragmatism 1 literalists 0
minor refactor of jsx_decoder
aspirational README with new api
refactor options to complete mission: more pragmatism
refactor test suite for additional completeness and clarity