Switched to vector_math
Fixed face normals computation
Removed old Vector classes and interfaces
Hide html.Path in three.dart and import with prefix to avoid collisions
Fixed .cross migration error
Merge pull request #67 from andersforsell/vector_math

Fixed additional .cross migration errors
Use Matrix4.copyInverse where appropriate
Merge pull request #68 from andersforsell/vector_math

Use Matrix4.copyInverse where appropriate