Additional changes.

The null-terminator would have been written one byte past the end
of the array (and there may have been an extra garbage character
in the index before it)

The original implementation was compressing the list,
throwing away empty strings.
The function that did that was pretty brain damaging.
I cleaned it up and adjusted so that it could return
list with empty values and without them.
The old function was turned into a wrapper and a new
high level function was intorduced to provide
ability to get both empty and non empty strings.

The previous patch included "config.h"
into the public header which caused all sorts
of redefinitions and warnings.

Added configurable key length.
Changed comments for the functions that
are currently not used and reserved for
future functionality.