Provide a feature not present into difflib, which is generate a colored diff

 from a diff file/string. This code is original form ERP5Subversion and was moved 
 to here for be used in general ERP5. 

 XXX The organisation of DiffUtils should be reviewed and reorganised if needed. 
 ie.: Move behaviour to a tool.



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32272 20353a03-c40f-0410-a6d1-a30d3c3de9de