#174 0.2.17 rename costcode, loses prev. costs

[Anonymous]

When a costcode is renamed (not only the description, but also the name of the costcode) then the costs are not found back - the costs items already assigned are not renamed, and don't show up in the overviews / reports any more because that costcode doesn't exist anymore.
Or maybe not be able to change the code is better if code is used in assignments? Or change existing costs also.