create a scanner and trigger indendepent of intereferometers for Eiger

Currently it is not possible to scan while recording images without having interferometers in the setup.

For future usage in other experiments, I implemented the classes EigerSwTrigger and EigerScanner that do not rely on interferometers. It will be needed e.g. for the Tapedrive if users want to scan a parameter (pH, temperature...)

Tested at P11 with a 1D scan, works fine. In the scanner the device to use is EigerSwTrigger , with the scanner EigerScanner