Kci to take kmer counter index as argument or somethign similar

[gonzalogacc]

sdg/src/sdglib/views/NodeView.cc

Line 76 in 52cd7c5

return dg->sdg.ws.kmer_counters[0].kci(llabs(id));

Nodeviews only compute kci values using the first kmer counter in the workspace, we need a way to point this to other kmer collections, maybe passing the index/name.