merge adjacent octave namespace blocks in libgui/graphics header files * BaseControl.h, ButtonControl.h, ButtonGroup.h, Canvas.h, CheckBoxControl.h, ContextMenu.h, EditControl.h, Figure.h, GLCanvas.h, ListBoxControl.h, Menu.h, Object.h, Panel.h, PopupMenuControl.h, PushButtonControl.h, PushTool.h, RadioButtonControl.h, SliderControl.h, Table.h, TextControl.h, ToggleButtonControl.h, ToggleTool.h, ToolBar.h, ToolBarButton.h, qt-graphics-toolkit.h: Merge adjacent octave namespace blocks.

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