Color: Simplifes hex notation parsing in .setStyle()

[ycw]

This PR simplifies hex to rgb in .setStyle()

when parsing 3digit hex: its safe to skip expansion (R -> RR etc) bc step size in ratio is always 1/15

before expansion: 15 steps (0x0,0x1,0x2,...,0xf), stepsize is 1, stepsize in ratio is 1/15
after expansion : 15 steps (0x00,0x11,0x22,...,0xff), stepsize is 17, stepsize in ratio is 17/255, also 1/15

when parsing 6digit hex: w/ .setHex(), hex str can be parsed just once