standard terrain generation and experimental trees

trees are very buggy and stone caves or ore generation is not yet
implemented
fixed trees, added biomes, removed unused methods

Fixed random leaf spawning by preventing trees from spawning on the edge
of the chunk which was causing them to warp the leaves to the other side
of the chunk. added biomes based on height (below 10 above water level =
beach / 5 above beach = extreme hills edge / above that = extreme hills)
removed unused methods in noise.cs
Delete MidpointDisplacement.cs
Delete Noise2d.cs
Delete PerlinNoise2D.cs
Delete Vector2.cs
Update Craft.Net.Common.csproj

remove unused reference to xna
Update Noise.cs

removed unused 'using microsoft.xna.framework' statement
Update Craft.Net.Common.csproj
Update Craft.Net.Server.csproj
Merge remote-tracking branch 'tuomas56/master'
Tweak terrain generation and reformat code
Initial 1.4.6 support, prevent server from crashing on client-side network errors
Fix problem with spawning underwater
Fix bug causing crashes when digging too low