Drop getLink API call

[RKrahl]

As already discussed during the collaboration meetings and announced via the mailing list: it seems that nobody is actually using the getLink API call. In that case, it is better to remove it.

In principle, it was not a bad idea to use hard links from the main storage to some user accessible directory to provide users a direct access to the file. But the current implementation in ids.server is somewhat to clumsy to be useful. It can be implemented as a separate script that could then be much easier adapted to the facility's needs. There is no need to have that integrated in ids.server.

According to current plans, we will deprecate that call in ids.server 2.0.0 and remove it in 3.0.0.