Adding Pilatus RoIs as Counter in the MeasurementGroup

The RoIs for the Pilatus detector are computed in dedicated VcExecutor tango devices. They have to run in a computer having access to the files written by the Pilatus. The best practice is to write the Pilatus files to gpfs. One of these VcExecutor tango devices is the one reading the file and making the calculations, the result of these calculations for the different RoIs is sent via a Clipboard tango device to the rest of the VcExecutors. The VcExecutor making the calculations as well as the Pilatus device have to be always added to the Measurement Group if we want to have any of the RoI. The rest of the VcExecutors have to be added if the corresponding RoI is needed. Section 11.2.10 describes the entries in the online.xml file.