* resources are described using Measure objects
   * stock can be queried in any unit
   * movements perform unit conversion

 * See following wiki articles:
   * HowToUseMeasures
   * TechnicalNotesOnUnitConversion

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@21253 20353a03-c40f-0410-a6d1-a30d3c3de9de