ZF-7100: Zend_Paginator can raise a divide by 0 warning
If itemCountPerPage is set to 0 or setItemCountPerPage is not called, a divide by 0 warning may be raised.
This could be avoided by either setting some default item count per page, or throwing an exception if the _calculatePageCount method is called without first setting a valid itemCountPerPage.
Throwing an exception should be prefered, as userland code could set the value to 0 if there is incorrect filtering. Relying on a php warning should not be correct however.