command-line tool: clarify that -D defaults to euclidean and check that p is positive if norm-p is specified
command-line tool: clarify that -D defaults to euclidean and check that p is positive if norm-p is specified

peterwittek/somoclu,peterwittek/somoclu,peterwittek/somoclu,peterwittek/somoclu,peterwittek/somoclu,peterwittek/somoclu