improved logdet, added wishart and invwishart
improved logdet, added wishart and invwishart

wgmueller1/pyhsmm,bikash/pyhsmm,theDataGeek/pyhsmm,fivejjs/pyhsmm,theDataGeek/pyhsmm,fivejjs/pyhsmm,fivejjs/pyhsmm,theDataGeek/pyhsmm,mattjj/pyhsmm,theDataGeek/pyhsmm,wgmueller1/pyhsmm,wgmueller1/pyhsmm,theDataGeek/pyhsmm,fivejjs/pyhsmm,fivejjs/pyhsmm,bikash/pyhsmm,bikash/pyhsmm,wgmueller1/pyhsmm,mattjj/pyhsmm,wgmueller1/pyhsmm