Fix handling of single-character FS.
Per POSIX spec (and the various implementations), a 1-char FS should be handled specially as a straight string split and not a regex. However, I had overlooked this, and was only doing this in the case of "\". This fixes things like FS="|" as reported by @shah in #29 (thanks!).
Bumped up minor version, seems like a fairly significant change rather than just a patch fix.
Also fix split() to have same behavior for single-char FS.
Fixes #29.