Valleys Mapgen 1.1

The biggest change from 1.0 : caves.
They are set by 4 3D noises, they looks a little like v6's ones.
There are big caves which has around 10-15 blocks size and connects to numerous others, and other smallers ones, the smallest possible is simply 1 block !

Ores have been reduced around 3 times. Now they appear at the same frequency than in default mapgens.