L1centrality 0.0.3

• Minor typo fix in the document.

• L1centLOC() and L1centEDGE() made more efficient.

• \() changed to function() for compatibility (L1centMDS.matrix()).

• The vertex multiplicity parameter eta generalized to nonnegative values (L1cent(), L1centEDGE(), L1centLOC(), L1centNB()). It previously accepted only positive values.