Parameterize visible width in SystemViewport

[juniorrojas]

Currently, it's hard-coded.

algovivo/algovivo/ui/SystemViewport.js

Line 212 in 7b0c5ae

worldWidth: 3.8,

We also need to update the grid rendering logic to adapt to arbitrary visible widths.

algovivo/algovivo/ui/SystemViewport.js

Lines 51 to 54 in 7b0c5ae

	x0: -3,
	y0: 0,
	rows: 4,
	cols: 10,