Non-unique menu item icons are not shown

Sketchup menus show icon only if the icon is globally unique - i.e. only one command has that icon. Otherwise, no icon is shown.

This is an unexpected pattern, which diverts from the pattern established by Toolbars, Sketchup Search, and other parts of Sketchup. This creates inadvertent effects.

Instead, we wish menus to always show the icons that is set in the command, unique or not.