GLTFModel does not set Texture encoding correctly for PBR materials

[xeolabs]

Textures loaded by GLTFModel should be sRGB when they are for PBR materials, and GLTFModel attempts to set the encoding property as such, however that property is read only. Therefore, they are always linear.

https://github.com/xeolabs/xeogl/blob/master/examples/js/models/glTFModel.js#L876

[yihoo]

When I use "pbrMetallicRoughness" in my model.gltf, it shows this following error:
Cannot set property encoding of # which has only a getter.
or
TypeError: Attempted to assign to readonly property.

----------------model.gltf---------------------------------
"materials" : [
{
"name" : "160802_mia337_001149_finalOBJ",
"pbrMetallicRoughness" : {
"baseColorFactor" : [
0.6400000190734865,
0.6400000190734865,
0.6400000190734865,
1.0
],
"baseColorTexture" : {
"index" : 0
},
"metallicFactor" : 0.0
}
}
],

So I'm wondering that my issue is relevant of your notification. Can you give me some advice to fix it?