Updates to the Cow: eyes, tongue, modes.

* [CODES_EXT,NEW] Added to_codes/2.
* [COWSPEAK,NEW] Added support for custom eyes and tongue to cowspeak.
* [COWSPEAK,NEW] Added modes support to cowspeak.
* [COWSPEAK,FIX] Wrapping mode would always be `word` (now it can also be `line` or `none`).
* [COWSPEAK,SC] Made it easy for the indent of the cow and the length of the cow to be adapted.
* [DCG_GENERIC,NEW] Added dcg_all//0 wrapper around dcg_all//1.
* [DCG_GENERIC,EXT] Added option `none` to dcg_reap//1.
* [DCG_GENERIC,FIX] dcg_line_wrap//2 did not write non-newline codes back to output.