Enhance test script to better test both algorithms

ENH: Added complementary function: SetScalarComponentFromFloat.  This is useful to create an image and draw seed points into it, since GetScalarPointer can not be used from scripting languages.

BUG: Fixing nasty mutex bug.  The mutex wast not being properly intialized and causes random crashes on a dual processer Linux box.  Now, check for proper initialization

of a vtkPolyData input.
Thanks to Philip Batchelor philipp.batchelor@kcl.ac.uk for creating and
contributing the class and Andrew Maclean a.maclean@acfr.usyd.edu.au
for cleanups and fixes

This commit was modified during conversion from CVS to merge the end
of the ParaView 0.6 release branch.  An equivalent commit did exist in
the original CVS repository: "2nd merge from ParaView-0-6 branch."

ENH: cleanup, move some utility classes/structs outside global space (remove all those _vtkInternalClass or VTK_LOOKS_LIKE_A_MACRO from doc). Also transform some structs to classes.

ENH: cleanup, move some utility classes/structs outside global space (remove all those _vtkInternalClass or VTK_LOOKS_LIKE_A_MACRO from doc).

ENH: cleanup, rename VTKVRC*Info to vtkVolumeRayCast*Info to comply with coding style/guide and clarify doc.

ENH: cleanup, fix VTK_ERROR_QUADRIC syntax (it's a struct, not a macro) and move it out of the global space.