Update README
Add s-split-up-to
Merge pull request #60 from Fuco1/s-split-up-to

S split up to
Fix s-reverse for Unicode combining characters.

When reversing a Unicode (multibyte) string, care must be taken to
reverse characters with their combining marks as a single unit,
maintaining their order.

* https://github.com/mathiasbynens/esrever
* http://www.cl.cam.ac.uk/~mgk25/unicode.html
Merge pull request #58 from skeeto/fix-reverse

Fix s-reverse for Unicode combining characters.
Add debug declarations for both macros, s-with and s-lex-format.
Merge pull request #61 from Bruce-Connor/macro-declare-debug

Add debug declarations for both macros, s-with and s-lex-format.