Bug 21196: Use replacement cost from the item type if not set at item level

Bug 21196: Use replacement cost from the item type if not set at item level

When circ rules are set to cap at item replacement cost, calcfine only
checks the price in the item record, not the default replacement cost by
item type.

Note: We do not take '0' into account, what if you do not want to set
a replacement cost for an item? It is how it is done in chargelostitem
so keeping the existing behaviour, but that may be considered as a bug (?)

Test plan:
- Set useDefaultReplacementCost to use
- Set a default replacement cost for a given item type
- Create an item of that type with a replacementcost=0
- Create a circ rule for that item type that accrues fines but caps at
replacement cost
- check the item out, forcing a due date in the past
- check that item in
=> Fines should have been generated

Signed-off-by: Caroline Cyr La rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>