[added] Lavastorm: Skull Cave

[jnils]

This is my first map ever!

Any comments are welcome

I could not have made it without SaintPeter's MAP guide.

I think we should combine SkullCaves POI's with Lavastorm's.
But not the other way arould.

<ImageStyle Name="lavastorm_2" displayname="Skull Cave" menugroup="Lavastorm (Island)" zonerect="-128, 120, 9, 257" availablerect="-128, 120, 9, 244" heightmax="-90" availablepriority="-1">
<ImageFrame Source="images/maps/map_lavastorm_3.dds" SourceRect="0,0,512,512" />
</ImageStyle>