candsetmaxpro should sample with replacement

[taalbrecht]

To see issue, try sampling more candidate points than there are rows in the candidate matrix

[taalbrecht]

Issue is this line:

DCDesign/R/ModelFrameProcessing.R

Line 513 in 4494fb0

designvec <- sample(c(1:nrow(D0)), npoints)

Note that this only affects initial seeding of the design, it is allowed to select replicate points from the candidate set as it iterates. Should still be fixed anyways.