made generateHeightMap a global func until I find a better place to put it
made generateHeightMap a global func until I find a better place to put it

this means a fake chunk can generate its heightmap

mcedit/pymclevel,ahh2131/mchisel,codewarrior0/pymclevel,arruda/pymclevel,ahh2131/mchisel,arruda/pymclevel,codewarrior0/pymclevel,mcedit/pymclevel