BUG #14874. Bring back "Scalar Opacity Unit Distance".

The "Scale" property shown on the old color map editor was really
setting the scalar opacity unit distance on the representation. Ensuring
that the "Scalar Opacity Unit Distance" property is exposed as an
advanced property on the "Properties" panel. Note, it's on the
Properties panel and not on the "Color Map Editor" panel.

Change-Id: I6cada928f9b21b3460679f7ba1de5911793cf42a
BUG: Fixed InvertTransferFunction.

InvertTransferFunction would set the property value in reverse order
(max->min). Fixed that. This has weird side effects like the property
being modified twice with InvertTransferFunction() was triggerred from
the UI.

Change-Id: Id5f1169103954aa6869412610cf640c452f66f75
Refactoring Python tracing support.

This is the initial commit in this effort to refactor the Python tracing
capabilities to produce more human readable trace by tracing
higher-level constructs that raw property changes.

This commit includes the basic implementaion with support for tracing of
core operations such as creation of pipeline objects, show/hide, and
some basic transfer function operations.

Also fixed missing ScalarRangeInitialized on PiecewiseFunction proxy.
Since PiecewiseFunction proxy didn't have ScalarRangeInitialized
property, we always ended up with the valid range including the default
values, which was wrong.

Change-Id: I8d5a60667617672e3b73bbbc9294f9abf912823d
Extensions to paraview.simple

* Added ColorBy() function to make it easier to color by scalars.
* Added FindView() method to get view by name.
* Added GetOpacityTransferFunction() to get opacity transfer function.
* Added view name indicators on the view frame to make it easier to
  address views.

Change-Id: I5af333558d15c94ca7ea936b5f473aade9f217a1
Added support to record creation/deletion of a view.

Also added ability to add trace items that are not nestable. Makes it
easier to trace Delete, for example.

Change-Id: Id8a60ceed308e48880d8ba2b9ce2ce68bc83be3f
Minor style cleanup.

Change-Id: I623c237a9b9959ec1aa7bda55f5f128440211a67
Added logic to trace view size.

Change-Id: Ia1a85c4739be068cfe45f264ad6bd2231578134e
Added support to trace scalar bar property changes.

Change-Id: I7fbbc251a8fd3c8a1a9b469b7bf12a01d1497b79
Added ability to trace saving of screenshots.

Added added API to simple.py to save multiple views as the UI does so we
trace it properly.

Change-Id: Ic249a70e1476a7242480078f70a67f9be29a2c6f
Add support for tracing plugin loading.

Change-Id: I64eb14cdbd924167cb830315d1b02e235100ebcd
Add ability to trace 3D widget visibility toggling.

Change-Id: I3ca73d6e61e084e3276a9153bf09b42548886beb
Add support for tracing exporting of views.

+ Added new class vtkSMViewExportHelper to replace
pqViewExporterManager.
+ Added API to simple.py to export views.
+ Added support to trace exporting of views.

Change-Id: Ib14cbc83a4fbe07065f337a04b57642e96f01286
Revamping UI components for tracing.

pqTraceReaction now support a single action for toggle start/stop
tracing. Tracing is stopped, if running before the application quits.
And finally, some GUI support for incremental tracing.

Change-Id: Ic8713899ce8e4a0852374ceec2a3df0a5f3ed45d
Basic animation scene tracing.

Added support to trace VCR controls and changing on scene properties
from the pqAnimationViewWidget.

Change-Id: I68266020a9a6cb4b281723053da6869b681d5e8e
More enhancments for animation tracing.

Added some extended support to trace animation cues and key frames. We
stop short of a full support for keyframes/tracks since we first need to
move the Qt-logic to server manager to provide a cleaner API for
creating cues, keyframes and initializing them.

Change-Id: I11bae445b0643912c6b7b166bf8cf37cbf615ca5
Add support for tracing view layout.

Added support for tracing view layout. Extended
vtkSMParaViewPipelineControllerWithRendering to automatically create
layout proxy if none exists. As a next step in this process, we should
update GUI to not automatically assign views to frames instead rely on
the servermanager to do it. That will make the code a lot simpler.

Change-Id: I3fd6554db83bfcda49200b62afbf5e690472ecbc
Trace change in input.

Change-Id: I201d73c6d001b325425f6fe5d0c017dcfecc6f2b
Trace rename and change in active source/view.

Change-Id: I09b36c41474d7745ed75d31ed74f7ac57de27476
Trace write animation.

This can be made more effective. Currently, just tracing what we
previosly traced.

Change-Id: If408e09701918f92bbd277b74d49c45065f35d11
Structuring of code to minimize duplicate 'ctor' logic.

Change-Id: Ib8b5e85e19a8c9f50a9fc5a72e6323cd6172788d