Add locality plotting for Arequipa

par(mfrow=c(1,2))
plot(mapLim) # to plot all the localities
locNames<-c("1.8.12","1.8.30")
plot.loc.arequipa(locNames,add=TRUE,col="blue")
Simplify samplexuv (faster?)

According to Paciorek: backsolveAndGaussianFieldSamplingPaciorek.pdf
Correction comment