V0.31.1 Released

Bug修改

• 解决GLTFMarker的symbol.animationNodes不起作用的问题， maptalks/issues#560
• 解决GLTFMarker.getGLTFJSON()方法没有返回完整的gltf json的问题， maptalks/issues#561
• 解决三维量算，高度始终为0的问题，并调整了label的位置， maptalks/issues#557

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Bug fixes

• Solve the problem that symbol.animationNodes of GLTFMarker doesn't work, maptalks/issues#560
• Solve the problem that GLTFMarker.getGLTFJSON() method doesn't return the full gltf json, maptalks/issues#561
• Solve the problem that the height is always 0 for 3D measure, and adjust the position of the label, maptalks/issues#557