Changes to SimpleKMeans to improve runtime and a couple of small fixes to SimpleKMeans and EM to fix behaviour for weighted data.

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@11290 e0a1b77d-ad91-4216-81b1-defd5f83fa92
From Eibe: Changes to SimpleKMeans to improve runtime and a couple of small fixes to SimpleKMeans and EM to fix behaviour for weighted data.

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@11291 e0a1b77d-ad91-4216-81b1-defd5f83fa92