also reduce manual memory allocation

For the palette mapping editor, problems were noticed when the threshold mode was set to unlimited.  The range of values was set using the range of floating point numbers which caused problems with NaN sometimes being displayed and the sliders were not functioning.  Now, when the threshold is 'unlimited', the maximum absolute value for all date within the file is found.  For 'unlimited' the range is now (-2 * file-abs-max-value, 2 * file-abs-max-value)

Updates for WB-393 Volume ROI Drawing: (1) Can now drag mouse to turn voxels on and off; (2) If a new volume is created, it becomes the top-most overlay; (3) New Volume Dialog can get volume parameters (dimensions, origin, spacing) from a CIFTI file.

In an attempt to resolve WB-474, Capture Image loses overlay in resulting capture: Added a call to repaint() immediately before calling captureImage() to ensure the frame buffer is updated.

More updates for volume editing including improved error messages and clean up of comments and code.

When assigning label coloring, if the label is not in the files 'group/name' hierarchy, go ahead and assign the label's color.

Fixed crash in overlay system when a chart is displayed in a tab.  The bug occurred during a recent update to yoke to the file selection status.

Fixed bug: If the volume underlay (anatomical volume) is turned off in the overlay toolbox, the selected slices do not change and then clicking the up or down arrow for a slice coord or index causes slices to jump to a much different location.

Fixed bug in culled orthogonal volume slice drawing that caused the selection to be off by a slice which sometimes caused the slice in the viewed axis to change.  Also added selection for volume voxel editing.

Starting on WB-393 Volume ROI Drawing.  Toolbar has been created and dialog for creating a volume file is functioning.

Resolve WB-473 Clicking Dense Connectome in Volume Montage is Innaccurate: When drawing a volume montage, the code was incorrectly using the coordinate of the selected slice (in toolbar) when drawing each of the montage slices.

Adjusted copyrights listing to be cover Vera*.ttf and more details on some files

Resolve WB-470: Add On/Off Status of Layer to Layer Yoking Functionality: Yoking of enabled status now only works for the same files and only if the file contains brainordinate data for surface AND volume.

When getting browser tabs do not include those tabs that are invalid to reduce invalid messages when enabling yoking with an incompatible number of maps.

Resolve/Fix WB-470: When overlays are yoked, the enabled/disabled status is only applied if the same file is in another yoked overlay.  The enabled/disabled status does not change the enabled status of a different file with the same yoking.

Reopen WB-470: Disable yoking of overlay enabled status since it is only supposed to take affect for the same file.

Resolve WB-472 Improve Help Searching: Search command limited listed hep pages to those containing the search query.  However, if a parent item did not contain the search text, its childen were not displayed even if one of the children contained the search text.  There are now two sections on the Help Dialog: Table of Contents that contains the help hierarchy and Search that contains all commands in alphabetical order with a search text box.

Resolve WB-470 Add On/Off Status of Layer to Layer Yoking Functionality: The enabled status is yoked with the selected yoking group.

For WB-471 Reload Layer to Constructor Dropdown: Update any visible overlay and map settings editors since they may contain the file that was reloaded and its palette may have been modified.

QGLWidget::grabFrameBuffer()  on Mac appears to grab the 'back buffer' so when capturing an image, call QGLWidget::grabFrameBuffer() twice to fix image capture.