This commit reindents the code with the following utility:
Utilities/Maintenance/vtk-reindent-code.py

This utility changes the positions of the braces so that they are no
longer indented relative to the code block they reside in.

The bash command line used was the following:

for d in Charts Common Deprecated Domains Examples Filters GUISupport \
         Geovis IO Imaging Infovis Interaction Parallel Rendering \
         Testing Views Web Wrapping; do
  for e in cxx cxx.in txx txx.in hxx hxx.in h h.in c c.in; do
    find "${d}" -name "*.${e}" -exec \
      python Utilities/Maintenance/vtk_reindent_code.py {} +
  done
done

generated via:
cd $VTKSRC
perl Utilities/Doxygen/doc_header2doxygen.pl --to ~/tmp/vtkheaders .
cp -r ~/tmp/vtkheaders/* .

The current dependency relationship in vtk is unclear and misleading.
This MR tries to rewrite them based on header files inclusion of headers
and source files in each module. Corner cases are considered and
modules are sorted in alphabetical order to facilitate future reference.
See details in my gitlab python based script project. In future we can continue
using this script to clean the VTK Dependency easily from
time to time.

It doesn't seem to have got everything, but it's a start.

Some resulting whitespace is suboptimal, but one day
we can fix that with clang-format. :)

Just ran this command:
run-clang-tidy.py -checks=-*,modernize-use-override -fix

(I actually had to build my own clang to make clang-tidy
output "VTK_OVERRIDE" instead of "override".)

vtk(.*)\(const vtk\1&\);\s*//\s*Not implemented[\.]*
to
vtk\1(const vtk\1\&) VTK_DELETE_FUNCTION;

vtk(.*)\(const vtk\1 &\);\s*//\s*Not implemented[\.]*
to
vtk\1(const vtk\1 \&) VTK_DELETE_FUNCTION;

vtk(.*)\( const vtk\1 & \);\s*//\s*Not implemented[\.]*
to
vtk\1( const vtk\1 \& ) VTK_DELETE_FUNCTION;

vtk(.*)\( const vtk\1& \);\s*//\s*Not implemented[\.]*
to
vtk\1( const vtk\1\& ) VTK_DELETE_FUNCTION;

vtk(.*) \(const vtk\1&\);\s*//\s*Not implemented[\.]*
to
vtk\1 (const vtk\1\&) VTK_DELETE_FUNCTION;

(operator\s*=.*);\s*//\s*Not\s*implemented[\.]*
to
\1 VTK_DELETE_FUNCTION;

After that, this finds basically nothing:

operator.*implemented

then manually reverted changed files in VPIC and KWSys folders.

SafeDownCast performs a series of virtual calls and string comparisons,
which is quite slow, especially when used in worker functions.

vtkArrayDownCast will switch between SafeDownCast and the more
efficient FastDownCast (only available for common vtkAbstractArray
subclasses) depending on whether or not FastDownCast is defined for
the specific array type.