Logging: The Great Shuffle

Logging: The Great Shuffle

I have split the new logging machinery to several files and started merging
it with the old logger.

The intention behind the split is that programs which do not create their
own log streams should include only <ucw/lib.h> (which brings only the minimum
set of symbols) and link only a minimalistic library module, while the programs
in need of the full power of the new logger include <ucw/log.h> and link with
all log-* modules.

I have also started renaming `ls_*' to `log_*', but so far only at a couple
of places.

(Beware, most parts of the trees are currently left in an uncompilable
state. Use `make obj/ucw/log-t' for a working test program.)