again and again
- the algorithm was very poor while calculatint the next alarm date,
  make it up to 1440 times faster
- modify a bit the test in order to take into account changes,
  thanks to changes, the test is going 4 to 5 times faster



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@11530 20353a03-c40f-0410-a6d1-a30d3c3de9de