This tool warns where macros should be using parens.
Fixed many issues it pointed out by either:
 - adding parens (which it can do automatically)
 - removed unused (or rarely used) macros
 - replacing macros with functions, notably vtkMath stuff

when testing for ogl support capture warning and error
output messages

The `LastOpaqueCheckTime` member in particular is used by `GetIsOpaque`
in a condition before being set and so must be initialized.  Otherwise
the condition may never be true and then the also-uninitialized value of
`LastOpaqueCheckValue` will be used, leading to unpredictable rendering.
Initialize all members to avoid such trouble.

Add a test for this feature.

Do the x window type check on windows as well

Cache the result provide an API for a string message
Verify that a shader program compiles

try creating a new window and destroying it

Avoid creating visuals, use correct args for pbuffer
try to leave state unmodified after the call

it was always trying to free the display

clean up the display connection if we test of ogl support

Working with Brian Paul to get a 3.2 osmesa context
requires changes to VTK and 11.2 mesa changes to work

Fixes vtkTextureObject::CopyToFrameBuffer() to discard source fragments
with alpha <= 0.

Mostly the issue was that variables are not set correctly when
gradient opacity was turned on. Most of these variables state
were dependent on whether or not shading was ON.

In some cases the backend may be defined by the cmakelists file
so only define it if it is not already defined

Switch to const char * which has more flexibility as backends
do not all have to be defined in VTK proper but can be
subclassed

Put the beckend enum into the RenderWindow class

Added an enum for the None selection

After reading the spec carefully realized that
we don't need to treat texture type as basis
for texture dimension. Also added note clarification
on what does size means.

Add a configured value in vtkRenderingOpenGLConfigure
for external applications to use and provide a new
method in vtkRenderWindow to get the backend at
runtime.

Move the offending macros to class-scope enums

Forgot to remove some debug code I was
using to test something

The object was allocated each frame in RenderToImage mode
and never de-allocated.

VTK no longer supports any compilers that do not provide this type.
Therefore all code conditional on VTK_TYPE_USE_LONG_LONG can be made
unconditional.  Leave the macro defined to tell dependent projects that
APIs using the type are available in case they still support versions of
VTK that make it conditional.

VTK no longer supports any compilers that have `__int64` but not a
`long` or `long long` that is 64-bit.  Therefore all code that is
conditional on VTK_TYPE_USE___INT64 is never used and can be dropped.

In ParaView, we have to supply the ui with pwf instances for the
opacity and size mapping.  The default pwf range is [0,0] to [1,1].
If you choose to size by an array with a range much larger than this,
ParaView crashes.  You can get around it by first open the pwf
editor and adjusting the x range to match an array you would like
to work with.

This fix could cause the mapper to be too slow, so I would like to
solicit other, more efficient approaches.

Fix edge flag being set and declared twice

This topic should make it so that the VBO and IBO only gets
rebuilt when it really needs to. Instead of relying on high
level MTimes it actually looks at the pieces of data that impact
the VBO or IBO respectively. The VBO can build without the IBO
rebuilding and vice versa.

Changed .+ to .* so that expressions such as "$x$" are detected
correctly.