Fixed a bug where numeric and date missing values were not being replaced properly.

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@11134 e0a1b77d-ad91-4216-81b1-defd5f83fa92
Fixed a bug where numeric and date missing values were not being replaced properly.

git-svn-id: https://svn.cms.waikato.ac.nz/svn/weka@11135 e0a1b77d-ad91-4216-81b1-defd5f83fa92