Added `s-split' alias for `split-string'.

According to the "What's with the built-in wrappers?" section of the
README the API should be complete even if it simply wraps emacs
functionality.  Therefore an alias `s-split' for `split-string' should
exist.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Changed `s-split' from an alias to a defun.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Added example for s-split.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
s-split: changed order of first two params.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
s-split: changed order of first two parameters in usage and test.

Sorry.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Merge pull request #20 from ruediger/s-split

Added `s-split' alias for `split-string'.