Changes:
1. new binning algorithm available - mdt.bin. This change is triggered by the changes in monobin package. 2. in MONOTONIC BINNING module, now special case field accepts only NA as an input. 3. sc argument of desc.stat now accepts NA only, not producing the error that numeric vector is needed. Condition !is.numeric(sc) replaced with ifelse(length(sc) == 1, ifelse(is.numeric(sc) | is.na(sc), FALSE, TRUE), ifelse(is.numeric(sc), FALSE, TRUE))