Removing redundant tree_data from the HTML / JS

[fedarko]

Not urgent, but there's code in _plot.py that does the following:

empress/empress/_plot.py

Lines 82 to 89 in 6e4bbd3

	for i, node in enumerate(empress_tree.postorder(include_self=True), 1):
	tree_data[i] = {
	'name': node.name,
	'color': [0.75, 0.75, 0.75],
	'sampVal': 1,
	'visible': True,
	'single_samp': False
	}

Since color and sampVal are the same for every node, it should be possible to omit these from the JSON. For trees with lots of nodes this would cut down on QZV size (and probably memory usage in the visualization) by a decent amount.

Even though attributes like color are changed dynamically in the visualization, we should be able to infer that -- for example -- a missing color for some node means that that node has the default color, aka [0.75, 0.75, 0.75] or whatever the default color is set to (#143).

[ElDeveloper]

See if possible to reduce as many of the attributes saved here.