ENH: Refactor VRPN Server/Client API
Allows for the following workflow : 1) Create a `VRPNDeviceClient` by specifying its URL (name@ipadress) and its type (see `DeviceType` class). The subclass `VRPNForceDevice` is setting the style to `PHANTOM_OMNI` by default for now. 2) Create a `VRPNDeviceServer` 3) Call `VRPNDeviceServer::addDeviceClient()` to add the client created on step 1). This will analyse the IP, name, and type of the device client to instantiate a VRPN device connection. The added devices are then stored in three `std:map` so the `mainloop()` can be called during the execution. Updated their use in `FEMSimulator` and `LaparoscopicCamera` examples.