fixed bug with setImage
implemented showImage
refactored arrow
refactored circle
updated cylinder and cube
added cone implementation
addeed test for text 2d/3d
refactoed plane
refactored WGrid
set background texture method
by default enabled tests vtk
improved background gradient
added painted cloud widget
added support of texture for mesh
updated mesh reading (texture support)
updated for compatibility with VTK6.0
added test for textured mesh
minor iteractor refactoring
resolved problem with multiple spin()/spinOnce()
merged background color with background gradient methods, updated tests to show description of scene