polylogs: New implementation of KobaNielsen()

polylogs: New implementation of KobaNielsen()

The old one was too ugly. The reason for all the ugliness
was 'performance', but this new implementation is not ugly
and has better performance. For example,

	L tmp = KN(8);
        #call KobaNielsen(8,3)

improves a lot (which would be relevant for 8pt zeta8 Jregs).

With the old implementation:

.03 sec + 15.13 sec: 15.17 sec out of 14.80 sec

with the new one:

0.01 sec + 0.76 sec: 0.78 sec out of 0.74 sec

Of course, the results for the computed Jregs don't change
(all data files in allNptJregs/ are reproduced).