merged jungle and bluish shadows

data/junglegrass.png

data/jungletree.png

data/jungletree_top.png

src/content_mapblock.cpp

src/content_mapnode.cpp

src/content_mapnode.h

src/keycode.cpp

src/mapblock_mesh.cpp

src/mapblock_mesh.h

src/mapgen.cpp

src/mapnode.h