Problem with exported mesh normals

The blender better collada exporter is not correctly exporting mesh vertex normals. It has the same sort of incorrect shading result that the native blender collada exporter has. The image below illustrates the issue.

The far left model has been modelled in blender and shows the correct normals shading. Next to it in blender is the reimported .dae model that had been exported via the better collada exporter. Both the triangulate and tangent arrays options were used for the export. It clearly shows that there are normals issues.

On the right side are 2 collada imports into Godot3. On the far right is the incorrect result imported as .dae from the better collada export. On the left is the correct result, still as a dae import. However to achieve this I had to export an obj from blender, import this into Cinema4D, export as a collada(1.4) to then import into Godot3.

This does show that Godot is importing a .dae file and it normals correctly (actually doing a better job than Blender, which cannot import its own exported dae correctly! It even imports the cinema4d dae export incorrectly). The problem lies with the blender exporter, with both the default blender collada and better collada exhibiting the same issue.

The zip file contains the blender(2.78) file and godot3 file.

[collada_normals_issue.tar.gz](https://github.com/godotengine/collada-exporter/files/1132695/collada_normals_issue.tar.gz)


Start by reproducing the issue with the attached Blender 2.78 and Godot3 files, using the Better Collada exporter with triangulate and tangent arrays enabled. Compare the exported DAE's mesh normals and shading with the source model and the OBJ/Cinema4D Collada reference; done means the Better Collada export imports with matching normals and shading.

Written by the indexing model from the issue text.