Add support for color and alpha in show_object

[TobseF]

To visually separate the pars I use different colors for my models:

show_object(partA, options={"alpha":0.2, "color": (64, 164, 223)}, name='Part A')

Also the alpha property is very useful to show hidden parts.

But the color option, will crash rendering:

## Oops! An error occured.

Can not load module. Standard_OutOfRange: Color out

I found out I can use predefined colors like RED, GREEN.
But using my own with RGB value, would be very nice🌈😊