Used the following command:

find . \( -iname *.h -and -type f \) -exec perl -pi -w -e 's/__vtk(.*)_h/vtk$1_h/g;' {} \;

Fixes many, but not all, clang -Wreserved-id-macro warnings.

Change-Id: I694ff053cb204c70e37b261296f496064d91fc07

Exclude ThirdParty, Utilities/MetaIO, and Utilities/KWSys as these
are maintained outside VTK.

Co-Author: Marcus D. Hanwell <marcus.hanwell@kitware.com>
Co-Author: Chris Harris <chris.harris@kitware.com>
Co-Author: Brad King <brad.king@kitware.com>

Move source files from their former monolithic VTK location to their new
location in modular VTK without modification.  This preserves enough
information for "git blame -M" and "git log --follow" to connect
modularized VTK files to their original location and history.

Co-Author: Marcus D. Hanwell <marcus.hanwell@kitware.com>
Co-Author: Chris Harris <chris.harris@kitware.com>
Co-Author: Brad King <brad.king@kitware.com>
Co-Author: Nikhil Shetty <nikhil.shetty@kitware.com>