Shape Tool Starter GUI/Function

[gabrielw-us]

Like #9 , just a first-draft GUI/function to test and iterate from.

• Click the Shape Tool button to activate it, and open the Shape Tool panel
• Click a shape icon in the opened panel to select it
• Clicked shape icon switches to blue "...On" icon
• Shape Tool button also changes to now display the current selected shape icon
• Aim ray at surface/grid, click to start creating shape, and click/drag through the shape's parameters (ie, width, height, depth)