Avoid dividing by zero, which it would appear can occur when DocVectors processes documents with multiple fields (as it checks for the occurrences of each term in each field)
Avoid dividing by zero, which it would appear can occur when DocVectors processes documents with multiple fields (as it checks for the occurrences of each term in each field)

git-svn-id: 08ea2b8556b98ff0c759f891b20f299445ddff2f@801 483481f0-a63c-0410-a8a8-396719eec1a4

svn2github/semanticvectors,tuxdna/semanticvectors-googlecode,svn2github/semanticvectors,svn2github/semanticvectors,tuxdna/semanticvectors-googlecode,tuxdna/semanticvectors-googlecode,tuxdna/semanticvectors-googlecode,svn2github/semanticvectors