Non-blocking vtk viewer alternative

[praxcom]

As far as I understand, existing efforts have not introduced an interactivly updateable viewer that is launched in a similar way to the vis.show function. Existing solutions dont use the native vtk viewer.
See #1784, #1786 and #1727

I am seperatly developing a parametric modeller, and want to display changes live, so being able to do something like the following would be greatly advantageous:

import cadquery as cq
from cadquery.vis import show_live

box = cq.Workplane().box(5, 2, 1).val() #initial geometry

viewer = show_live(box) #initial view

def gui_callback(event):
    # Do stuff...
    box = #...updated geometry 
    viewer.update(box) #update the view, no blocking on either side

### GUI CODE + LOOP