Model tree helper

Types

`A3DStatus`	`A3DTreeCompute()`
`A3DStatus`	`A3DTreeGetRootNode()`
`A3DStatus`	`A3DTreeNodeGetChildren()`
`A3DStatus`	`A3DTreeNodeGetParent()`
`A3DStatus`	`A3DTreeNodeGetEntity()`
`A3DStatus`	`A3DTreeNodeGetName()`
`A3DStatus`	`A3DTreeNodeGetTransformation()`
`A3DStatus`	`A3DTreeNodeGetNetTransformation()`
`A3DStatus`	`A3DTreeNodeGetNetVisibility()`
`A3DStatus`	`A3DTreeNodeGetNetStyle()`
`A3DStatus`	`A3DTreeNodeGetGeometry()`

group a3d_modelfile_helper

Tools and structure data to use for quick implementation of a model tree.