Revert the previous changes : the right way is not to generate additionnal lines, but to offer the possibility to input the check reference range end in the case of a traveler check.
Factorise new code with existing one.
Add a check to avoid a "substracting str to str" error when converting the check reference to int fails.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13273 20353a03-c40f-0410-a6d1-a30d3c3de9de