Take Two

I just got round to releasing a new version of sl. There is some new functionality, but otherwise no changes. From the Freshmeat announce:

Added the sl_filter() function. With it you can extract all (or the first N)
nodes matching a certain criteria from any list. Also some minor rework of the
build process, abolishing recursive make.

Thanks to Richard Spindler for providing tests and the original implementation of this function.