Allow negative time for worklogs

We need to be able to create negative worklogs so that big corrections can be done.
The use case for this feature would be that accounting needs to be able make big corrections for a past time period. However, without the option to log e.g. "-100h" this would only be possible to achieve by removing/adjusting a lot of worklogs from issues manually. Not only is this a lot of overhead, but it also distorts the worklogs of the employees which don't add up afterwards (or it would be necessary to log their billable work to a ticket for non-billable work so that it adds up again).For a big company this gets very tedious or even impossible to manage.