fix TerrainGeometry->_getHeight method->convert r,g,b from 0-256 to 0-1:now r,g,b divide 256.0 instead of divide 255.0
fix TerrainGeometry->_getHeight method->convert r,g,b from 0-256 to 0-1:now r,g,b divide 256.0 instead of divide 255.0

yyc-git/Wonder.js,yyc-git/Wonder.js,yyc-git/Wonder.js