[Paraview] writeing vts files

[Brad King]

don fisher wrote:
> 1) The one that is 4622 lines long is xmlparse.c.
> 
> 2) There are many defines in the xmlparse.c code, but there is an entire 
> file called vtl_expat_mangle.h that redefines function names. This is 
> probably required to accommodate C++ overloading, but it makes debugging 
> difficult. The debugger tracks compiler mangled names without any 
> confusion.
> 
> 3) xmltok_impl.c and vtkSetGet.h are examples of where I thought inlined 
> functions might be more appropriate than the #defines which are not 
> expanded by the debugger.

Files in directories like VTK/Utilities/vtkexpat and Utilities/vtktiff 
are external libraries that we import into VTK's source tree to reduce 
dependency and versioning issues.  The "mangle" headers make sure the 
VTK versions of the libraries do not conflict with system versions of 
the libraries and are implemented as macros to avoid making big changes 
to outside code that we might import again when a newer version is 
available.

-Brad