d3graph.set_node_properties error when provided with a list of colors

[LoePhi]

Description

Using d3graph.set_node_properties() with a color-parameter like ['A','A','B',...] results in a ValueError raised by _check_hex_color():
'[color] contains incorrect length of hex-color! Hex must be of length 7: ["#000000", "#000000", etc]'

Expected behaviour

The color-parameter is used together with cmap to generate a list of hex-colors

Sugested fix

Apply _get_hexcolor() to the color parameter if the user passed a list of str.