Assimp conversion output of FBX file is not ideal

FBX import result via assimp looks fine at the first glance, however, if we look into the details, there are some strange quirks that makes QtQuick3D application developer hard to customize the scene.

For example,

• Light power/intention is lost (actually, it seems to be represented as light color factors, however, almost impossible to recover.)
• Some strange transforms are added.
• Origin of each mesh becomes that of the parent. (making reusing the same mesh impossible.)
• Some rotation animations seems to be lost probably due to the previous problems. (And hard or imossible to recover in the QML code...)
• All the keyframe animations except position/rotation/scale are ignored.
• Keyframe animation outputs are incorrect in some conditions. (assimp bug)
• All cameras are treated as PerspectiveCamera.

Probably, it will be better to use FBX SDK in the future.