Add icons or labels to toolbar MenuButtons that appear when window width is decreased.

Tools

• Select: Too wide (added icons, moved misplaced icons)
• Node: OK?
• Shape: OK
• Rectangle: OK (added label "Corners")
• Arc: OK (added label "Angles")
• Star: OK (added label "Parameters")
• Box: No changes
• Spiral: No changes
• Pen: OK
• Pencil: Too wide, only "Mode" collapses (added label "Modes")
• Calligraphy: OK (added labels "Parameters" and "Options", changed order of popovers and switched one from "Width", etc. to "Caps", Wiggle", and "Tremor", swapped order of "Wiggle" and "Tremor" to match 1.3)
• Text: OK (added icons)
• Gradient: OK (added label "Options") Could be optimized
• Mesh: OK (added label "Options")
• Dropper: No changes
• Paint Bucket: OK (added label "Parameters")
• Tweak: OK (added label "Channels")
• Spray: Too wide (added labels "Mode", "Parameters", "Apply", "Pick", changed Popover3 to hide "Scatter" and "Focus" rather than "Width" and "Amount"). Fixed incorrect offset adjustment.
• Eraser: OK (added label "Parameters")
• Connector: No changes
• LPETool: No changes
• Measure: OK (added labels "Options", "Options")
• Zoom: No changes
• Pages: No changes

Adjusted number of digits shown in spinbuttons to match 1.3.

The visibility of some widgets depends on the mode chosen. This is not always reflected in hiding the GtkMenuButton when those widgets are moved into drop-downs. Tweak, Spray, Eraser

The Pencil tool sets the minimum width needed for the Inskcape window. Unless this toolbar is allowed to be narrower, there isn't a great need to allow other toolbars to shrink smaller so some of the MenuButtons could be removed.

Fixes #4884 (closed)