Remove makeTreeBody. Use makeReportTreeList for rendering a domain tree instead.

Set a base category in each report tree. I don't know if this is really necessary.
Cache getStatSelectExpression.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@8121 20353a03-c40f-0410-a6d1-a30d3c3de9de