* Use templated version to add a trigger.

A trigger is needed for Poll type inputs. Still it can not be used for
Devices. Here one has to call addSource manually.

* No need to use a trigger. Fix connections by moving all to history.

Trigger is only needed for DeviceModules. So in case of device addSource
still needs to be used, because no tags are present for devices.

* Add option to specify the directory where history will appear in CS.

* Remove CS tag not needed any more.

* Update documentation.

* Update documentation of logging module.

* Remove CS tag not needed any more.

* Remove parameter not needed. AddSource for ConnectingDeviceModule. Docu.

Connecting a device only works if the PVs are readonly! So one has to
use the logical name mapping backend. This also allows to select only a
subset of the device PV to be added to the history module.

Now one can add ScalarOutput and ArrayOutput variables to the history modules by using tags.

This is still not nice. Now for every data type an individual module needs to be created.