For testing purposes only, added an partial implementation of oblique slice drawing that uses a 3D Texture and offers better performance than the current oblique implementation.  It must be enabled using an item in the Develop Menu.

WB-855 Change All Slice Plane Default to Row: Fix for older scenes prior to the addition of the All Slice Planes value.  Theses older scenes need to restore to GRID and ignore the user's preference for the layout.

WB-855 Change All Slice Plane Default to Row: Slice order in ROW is not Parasagittal, Coronal, and Axial (consistent with other layouts).  Preference default is now ROW.

Resolve WB-853 Converting annotation labels from one mesh to another: Old parameters (-source-surface and -target-surface) were removed.  Users must use "-surface-pair" for source and target surfaces.

Resolve WB-855: Change All Slice Plane Default to Row: The slice planes layout for new tabs is now set in Preferences --> New Tabs.  The default layout remains GRID as it has always been.  Users desiring ROW or COLUMN just need to change the Preference one time.  Note that the All Slice Planes Layout is a 'per tab' property and affected by yoking.  Thus, if new tabs are "Yoked to Group A", the All Slice Planes Layout will be that associated with  "Tab A" and may be different than the Preference for All Slice Planes Layout.

Improved usage of new CaretPreferenceDataValue for the crosshair gap preference so that user just sets/gets gap value from CaretPreferences.

WB-851 Cross-hair improvement: Default crosshair gap in preferences to 0.0 so that crosshairs do not have a gap by default.

Fixing compilation errors on Linux systems from use of std::array initialization with another std::array.

WB-857: Absolute paths were also found for surfaces used for volume surface outline.  This has been corrected to use ScenePathName so that the file names are absolute in memory and relative in the scene file.

More on WB-857: Removed code that was replaced by new relative path for writing scene.  Older code for restoring remains and is used with scene files created prior to this bug fix.

WB-857: Older code fixed a problem with identical file names by saving the full path into the scene file and then performing a 'right-most characters" match to restore the data. While it works, we should not have absolute paths in the scene file.  It was probably done this way since the file was the name of a scene XML element and the scene path absolute/relative mechanism only works on 'ScenePathName' elements.

Now the name of the element is just the name of the file (no path).  A new child element, using a ScenePathName element has been added that is the absolute path in memory and a relative path in the scene file is now used to properly restore the data file's scene data.

Partial implementation of WB-851 Crosshair improvement: Adjustable gap is functioning for orthogonal mode and saved/restored from scenes and in preferences.  Next is adding gap to crosshairs in oblique mode.

For wb_command -annotation-resample; Added '-surface-pair <source-surface> <target-surface>' option.  It replaces the '-source-surface' and '-target-surface' options that are still available but produce a depreciated warning.  The old options will be removed in about a week.

Correct compilation error in OperationShowScene caused by a failure of my build system properly detecting MesaGL libraries (without mesa, some code is not compiled that contained a function with changed parameters).

Added ON and OFF buttons to the Annotation controls in the Features Toolbox.  This allows the user to select groups of annotations while using the shift/ctrl keys and change the display status of a large numbers of annotations.  Prior to this change the user had to turn on/off each annotation individually by clicking its checkbox.  In addition, the user may also select annotations in the Features Toolbox while NOT in Annotation Mode so that groups of then can be turned on/off (note that the "sizing handles" that are drawn around each of the selected annotations are only displayed in Annotation Mode).

In Features ToolBox --> Annotations, add On and Off buttons so that user can select more than one (often many) annotations in the list of annotations and turn their display status checkboxes on and off.

Fix problem with "Enter Full Screen" not functioning in the View Menu on MacOS 10.14 and Qt 5.12 by setting the "Enter Full Screen's"  'Menu Role' to QAction::NoRole.  This problem may have affected other versions of MacOS and/or Qt.

Fix problem with "Exit Tile Tabs" not displayed in the View Menu on MacOS 10.14 and Qt 5.12 by setting the Tile Tab Menu's "Menu Role" to QAction::NoRole.  This problem may have affected other versions of MacOS and/or Qt.

WB-852 Volume Scrolling: Incrementing of volume slices in Volume View and in Orthogonal mode is now performed by dragging the mouse in a vertical direction.  The change in slice indices is a function of how slow or fast the mouse is moved.

Fix compilation error on linux.  Compilers do not support iterating directly with an initializer list.

WB-846 Change default palette to absolute percentile: While changes for palette initialization were made to PaletteFile::setDefaultPaletteColorMapping, it is never used.  VolumeFile::validateMembers() has been updated so that if a volume's map does not have palette color mapping (and is not a label volume), the default will be use to use the Absolute Percentile and the ROY_BIG-BL palette except for an ANATOMY volume with one map which will use the GRAY_INTERP_POSITIVE palette.

Add more macro support for widgets on surface properties dialog and improvements in creation and management of macro widget actions.

Added some static methods to make it easier to issue command events such as update surface coloring, update user-interface, update graphics.

Added WuQMacroWidgetAction class that allows widgets in dialogs modal and non-modal dialogs (note: widgets may not exist when macro is run) to function with the macro system.

Resolve WB-850 Data Tooltips should show top-most enabled overlay.  Data tooltips was always showing the top overlay, even if the top overlay is DISABLED.  This has been corrected to show the top-most ENABLED overlay in the tooltip.

Remove fixes for  'initializer list' compilation warnings seen on Mac build as it causes a compiler error on Linux systems.  It appears that this warning on Mac may be invalid (see https://stackoverflow.com/questions/13905200/is-it-wise-to-ignore-gcc-clangs-wmissing-braces-warning).

WB-842 Opening a spec or scene file from Finder on MacOS Mojave (10.14) does not work: This works by the MacApplication class receiving a QFileOpenEvent and then passing it along through the Workbench event system to GuiManager.  It seems that in MacOS Mojave, this is happening very quickly, before GuiManager is created.  So, move the creation of GuiManager to just after the creation MacApplication.