Hacky work on biome tinting

Currently this requires python-gearman, gearman-java, and a java SDK.

This code will probably be all thrown away, but if you really want to
play, first compile Biome.java, then run the resulting Biome.class.
Note you'll probably need to hack the signatures out of minecraft.jar to
get it to run.

Then copy grasscolor.png into the cwd, and run gmap.py as usual.

It is slowwwww.  Perhaps running Biome.class on multiple machines might
speed things up?

Here's the kind of output produced: http://smp.em32.net/biome_test/

chunk.py

@@ -528,6 +528,9 @@ class ChunkRenderer(object):
             if not t:
                 continue
 
+            if blockid in (2,18): # grass or leaves, tint according to biome
+                t = textures.tintForBiome(t, (16*self.chunkX) + x,y+(16*self.chunkY))
+
             # Check if this block is occluded
             if cave and (
                     x == 0 and y != 15 and z != 127