closes #447: take ascertained columns in account when setting up mutation rate weights in BEAUti when fixing the mean mutation rate
closes #447: take ascertained columns in account when setting up mutation rate weights in BEAUti when fixing the mean mutation rate

CompEvol/beast2,tgvaughan/beast2,Anaphory/beast2,Anaphory/beast2,tgvaughan/beast2,CompEvol/beast2,CompEvol/beast2,Anaphory/beast2,Anaphory/beast2,CompEvol/beast2,tgvaughan/beast2,tgvaughan/beast2