To install this package, run in Emacs:
M-x package-install RET visual-fill RET
This `visual-fill-mode' minor mode basically "unfills" paragraphs within jit-lock, hence without modifying the buffer. Combined with the normal line-wrapping this performs a kind of "auto refill" which can be more or less sophisticated depending on the line-wrapping used. For best effect, combine it with `visual-line-mode' and `adaptive-wrap-prefix-mode'.