Network.show_buttons() and network.set_options() behave unexpectedly when ran on the same network.

[YouGuessedMyName]

To reproduce, run (not in a notebook).

from pyvis.network import Network
import networkx as nx

g = Network()

g.from_nx(nx.florentine_families_graph())
g.show_buttons(filter_=['nodes'])
g.set_options("""
var options = {
    "nodes": {
        "color": {
            "background": "rgba(252,39,99,1)"
        }
    }
}""")

html = g.generate_html("example2.html")
with open("example2.html", mode='w', encoding='utf-8') as fp:
        fp.write(html)

Expected behavior: The Florence family graph, with interactive node sliders/color pickers.
Actual behavior: An empty graph with no interactive node sliders/color pickers.

[linusheck]

This might be the same issue as #81