[vtk-developers] Added __WRAP__ preprocessor macro to replace BTX

[David Gobbi]

Hi All,

As you all might know (or maybe not), the wrappers ignore //BTX //ETX
now, except when wrapping code outside of the VTK source tree. This
has been the case for several months now.  I consider the //BTX
markers in the code to be vestigial, and will push to have them
removed once the 5.6.x series is finished.

Inspired by the "#ifndef__GCCXML__" blocks in ITK, I have added a new
"__WRAP__" preprocessor symbol that can be used to block off code:

#if !defined(__WRAP__)
// code exclusion section
#endif

The wrapper's new preprocessor will ensure that code in these blocks
never reaches the wrappers.  This should be used sparingly, because
when a VTK header file breaks the wrappers, it should be considered a
bug in the wrappers, not something to be fixed in the header.

   David