Added fix for errors caused when other view type is selected
Added check that active object is the one expected

This avoids trying to set the Italic property on non-MADAILogo text
sources.
Removed temporary explicit dependency on vtkRenderingMatplotlib

This was required by a bug in ParaView that has been fixed
Added Threshold Points filter

The default Threshold filter in ParaView works
only for data sets with cells. As such, it
doesn't work on particle data sets with no cells
without some kind of workaround.

The Threshold Points filter does work with
particle data sets with no cells.
Initial skeleton of VRPN server starter

It doesn't yet start a VRPN server.
Added starting/stopping of VRPN server thread
Added vrpn_3DConnexion_Navigator server

Server should be working now, but still need to test.
Removed some output and reduced the thread sleep time between calls to mainloop()
Removed unneeded member variables
Removed todo comment
Removed informative messages
Changed name of device to 'spaceNavigator'
Removed sleep between calls to mainloop()
Updated to build with VRPN

Made pass through code to make variable substitutions
the least ambiguous kind.
Added FindUSB1.cmake file

Needed to find libusb1.0 on linux
Added local CMake directory to module path
Added libusb1.0 dependency
Had to remove PointSprite plugin from ParaView build

It was causing a build failure.
Added plugin.cmake file ParaView now requires to find plugins
Fixed call to GetCMakeCacheValue