Applied patch from Jan Heller that ports BablFishPath class to the new

Applied patch from Jan Heller that ports BablFishPath class to the new
list API and the list API is a bit expanded. Further, the algorithm
for generating the shortest conversion path is reformulated to be more
readable and comprehensible and thoroughly commented. The algorithm
for processing the conversion paths is reformulated and commented.
Also contains minor readability cleanups and speedups.
* babl/babl-classes.h:
* babl/babl-conversion.c:
* babl/babl-db.c:
* babl/babl-fish-path.c:
* babl/babl-fish-stats.c:
* babl/babl-fish.c:
* babl/babl-list.c:
* babl/babl-list.h:
* tests/babl_fish_path_fitness.c:

svn path=/trunk/; revision=301