ENH: special: move more functionality into _complexstuff.pxd
ENH: special: add xlogy function
GEN: special: regenerate files
ENH: special: add xlog1py
GEN: special: regenerate files
DOC: special: add xlogy, xlog1py
Merge pull request #469 from pv/xlogy

ENH: special: add xlogy = x*log(y) with xlogy=0 for x=0