Better drawing API

[cwervo]

Native way to draw strokes, rectangles, lines.

Right now we use Display.tcl to draw to the Linux framebuffer & it doesn't have parity with the Tcl/TK environment on desktop.

Ideally (example syntax, I'm not married to it), something like:

Draw a small white circle on $this
Draw a small circle # assumed to be centered on $this, color is `white`
Draw a circle       # assumed to be centered on $this, color is `white`, defaults to `small`

Draw a circle at (100, 100)
Draw a circle 100 to the left of $this # take the top right corner $this as origin for drawing

[osnr]

Fixed in #103