#4 Support rotation in Flame 2.3

[Ronald Hordijk]

Flame v2.3 support rotation keyword, use this one in the
export.

<flame time="100" palette="77" size="640 480"
scale="240" oversample="3" filter="1" quality="1800"
batches="200" brightness="4" gamma="4" vibrancy="1"
hue="1" parents="163" rotate="180">
<xform weight="0.951" color="0.39" symmetry="0.9"
spherical="1" coefs="-1.16304 -0.326204 0.313699 -
1.02237 0.26248 -1.01138"/>
<xform weight="0.049" color="0.56" polar="0.11"
hyperbolic="0.61" bent="0.16" coefs="0.623994 -
1.42941 -0.556625 0.611553 0.385985 -0.273701"/>
</flame>