New structure for XML parsing - Vehicle sensors - ROSInterfaces. To add a new device, 3 files must be changed in addition to scene xml and new source files:  CMakeFileLists.txt - add device/interface C++ source.  data/scenes/UWSimScene.dtd - add new driver schema  src/SimulatedDevices.cpp - add #include and add 1 line into initFacotries() function

Next commit will contain an example...
Example Device/ROSInterface with type=="echo".
To see it in action run UWSim with cirs.xml and execute `rostopic echo /g500/echo`.