Minor performance fix
	modified:   VortexDetector.C
Add description
	modified:   ../../VTK/VectorFieldVTK.cxx
multiblock support (not tested)
	modified:   ../../VTK/examples/StreamlineSimpleVTK.cpp
Autodetect plot3d format
	modified:   ../../VTK/examples/vec2vti.cpp
	modified:   ../../renderer/examples/gcbStreamline.cpp
Drastically increase the color assignment speed