This generates gravel in Extreme Hills M biomes.
Re-added empty line.
Normal extreme hills (plus) now generate a stone/grass pattern.
Changed tbGravel. Vanilla has 3 layers of gravel and then stone.
Extreme Hills M biomes now generate gravel, stone and grass patterns.
Simplefied Extreme Hills M pattern select.
Merge pull request #472 from mc-server/Extreme_Hills_M

Extreme hills