remove IOVLock hacks

currently, every algorithm needs a specific data dependency: IOVLock.
This relates to interaction with the conditions. most likely, @clemenci can elaborate a bit more if people would like to have the details.
Because i did not want to obscure the user code with this additional dependency, its hacked into core.py at a couple of places.
As soon as this dependency is not anymore needed (the iovlock dependency is hack), we can get rid of all these hacks in core.py